Is this homebrew Dex-based barbarian subclass (Path of the Striker) viable and/or balanced?

Question

Is this homebrew Dex-based barbarian subclass (Path of the Striker) viable and/or balanced?

It is based off the Berserker, with a focus on incorporating Dexterity into its features rather than Strength. It also replaces base class features with similar ones.

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Path of the Striker

For some barbarians, rage is not about brute strength, but rather superior agility. The Path of the Striker is a path of speed, decimating opponents before they even realize they’ve been beset upon. As you enter the striker’s rage, you deliver precise blows in rapid succession.

Striker’s Rage

Starting when you choose this path at 3rd level, your rage is more focused. Instead of the standard benefits of rage, you gain the following instead:

While raging, you gain the following benefits if you aren't wearing heavy armor:

• You have advantage on Dexterity checks and Dexterity saving throws.
• When you make a melee weapon attack using a finesse weapon, you gain a bonus to the damage roll that increases as you gain levels as a barbarian, as shown in the Rage Damage column of the Barbarian table.
• You have resistance to bludgeoning, piercing, and slashing damage.

In addition, your Reckless Attack feature is replaced with the “Desperate Attack” feature.

When you reach 18th level, your "Indomitable Might" feature is replaced with the “Predator's Pursuit” feature. When you reach 20th level, your "primal champion" feature is replaced with the “Speed Demon” feature.

Desperate Attack

When you make your first attack on your turn, you can decide to attack desperately. Doing so increases your attack range on melee weapon attack rolls using finesse weapons by 5 feet during this turn, but you provoke opportunity attacks after your attack as if you had moved closer to attack and returned to your original position. This effect lasts until your next turn.

Fleet of Foot

Beginning at 6th level, you can ignore the effects of non-magical difficult terrain while raging. In addition, your speed is increased by an additional 10 feet while raging, and you can maintain your rage by taking the dash action and moving at least 10 feet beyond your base walking speed.

Blitzkrieg

Beginning at 10th level, You can use the dash action as a bonus action. Once per turn, after moving at least 5 feet towards a creature and making a successful melee attack, your damage is increased by 1d4 damage for every 5 feet you have moved towards the creature.

Whirlwind Sprint

Starting at 14th level, when you move past a creature, it must succeed on a strength saving throw or be knocked prone. The DC for this save is 8 + proficiency + your dexterity modifier. This effect happens before opportunity attacks.

Predator's Pursuit

Beginning at 18th level, if an opponent takes the disengage action and moves away from you, you can use your reaction to follow them up to a distance equal to twice your dexterity score.

Speed Demon

At 20th level, you embody speed. Your Dexterity and Constitution scores increase by 4. Your maximum for those scores is now 24.

Answer 1

This subclass gives more features than any other Barbarian subclass

A Barbarian subclass gets features at levels 3, 6, 10, and 14. As you said, this subclass replaces features outside of the subclass from the base class, which no other subclass does. I would expect these to be alternate class features, as in Tasha's, rather than this being something exclusive to this subclass, as it is essentially getting subclass features at levels 2 (Retroactively), 3, 6, 10, 14, 18, and 20.

Fleet of Foot is a little awkwardly worded

Fleet of Foot says:

you can maintain your rage by taking the dash action and moving at least 10 feet beyond your base walking speed.

This is quite confusing, consider defining what exactly your "base walking speed" is. In addition, the lower limit of movement can be cumbersome to remember.

Blitzkrieg, in addition to being a bit over tuned, is in need of some clarification.

Blitzkrieg I can see is attempting to help compensate for the fact that a Striker otherwise wouldn't be able to keep up in damage with a regular barbarian, being unable to use Polearm Master or Great Weapon Master and lacking fighting styles to supplement the one handed weapon and shield strategy it is directed towards. But the adding of extra d4's of damage is quite clunky, and a little silly in practice.

There is no other feature like this in the game to my knowledge, and a player might go out of their way to maximize the damage they can deal with this, perhaps calling on other players for spells such as Haste, taking the Mobile feat, races with high walking speeds, etc. Could a player move back and forth during their own movement to increment extra 5ft moves towards the enemy if there is not enough room? The feature does not grant you movement that must be used to move towards a creature, like the Aggressive trait does. Consider this example that I think is legal to my understanding:

A Tabaxi Striker under the effects of the Haste spell is about 25ft away from the enemy, he moves 20ft forward, 5ft back, and 5ft towards the enemy again until they run out of movement after doubling their move speed. And do that over and over again, therefore each 10ft moved translates to +1d4 damage after the first 25ft, they use their Haste action and Bonus action to dash, ending up with hundreds of d4's if they hit one of their two attacks. Each d4 is essentially an additional 2.5 damage. Obviously this is an extreme example but it takes much less than this for it to become something silly. I would add a limit on the additional damage it can do, and d4's are a rather inconvenient dice to be rolling many of as people usually don't have more than a couple.

In addition, this Unearthed Arcana article says this about 10th level barbarian features:

The 10th-level features of both Primal Paths speaks more to the interaction pillar of the game than to combat; be wary of replacing or altering them to add combat potency.

Note that this article was written when the only Barbarian subclasses were the Berserker and the Totem Warrior. By being a feature the explicitly boosts combat ability, Blitzkrieg is a little out of place.

Also, a small note about style, I would rename this feature to something vaguely fantasy or RPG related, but that's just me.

Whirlwind Sprint is kind of weak and unclear

What exactly does it mean to move past a creature? Move through their threatened area? It should be very particularly worded and easy to remember.

For a feature this high level, it doesn't really do much.

Predator's Pursuit also suffers from awkward wording

To my understanding, the terminology "follow" doesn't exist, you may want to phrase it "You may use your reaction to move a number of feet equal to twice your Dexterity score."

With some abuse, this could be Barbarian but better.

One of the Barbarians main weaknesses is rather poor armor class which isn't completely solved by their high hit points and resistance. Allowing a barbarian player to fix that problem at no real cost to their damage or overall survival ability is not ideal. The added mobility does serve to mix up the Barbarian playstyle, however.