Yes, sequester can be somewhat defeated to varying degrees.
The description of sequester states (emphasis mine):
By means of this spell, a willing creature or an object can be hidden away, safe from detection for the duration. When you cast the spell and touch the target, it becomes invisible and can't be targeted by divination spells or perceived through scrying sensors created by divination spells.
Other effect details are explained, the object or creature is frozen in time until a condition is met, or:
This spell also ends if the target takes any damage.
(Note that while the description says the target can be hidden away, it does not state that the target has the hidden condition/state)
Seeing the Sequestered item
The invisible condition is defined in PHB p291:
An invisible creature is impossible to see without the aid of magic or a special sense.
As well as being able to detect via sound but it's in suspended animation, assumed silent and still.
See invisibilty specifically states:
For the duration, you see invisible creatures and objects as if they were visible
Which specifically allows you to visibily scan the area. But is that targetting the sequestered item with divination magic? No, see invisibility targets the person who was granted the ability to see invisibility. A DM may or may not agree mind you.
Either way, if the target has been removed from the area, or is not nearby while looking, it cannot be targeted by divination magic to locate it.
Detect magic is also a divination spell that would be targeting the one granted with magic detection.
you sense the presence of magic within 30 feet of you. If you sense magic in this way, you can use your action to see a faint aura around any visible creature or object in the area that bears magic
You would first need to be within 30 feet, allowing you to sense it, then use an action to see a faint aura, which only with see invisibility would the sequestered item be visible to you. You could sense it even if invisible, but no visibility without see invisiblity.
Truesight's description specifically states that you can see invisible objects and creatures. This comes with the boon of no divination magic being involved at all for the sake of DM disagreement.
Dispel Magic on Sequester
Dispell Magic is described as such:
Choose one creature, object, or magical effect within range. Any spell of 3rd level or lower on the target ends. For each spell of 4th level or higher on the target, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a successful check, the spell ends.
Sequester is a 7th level spell. So if you managed to find the object, you could target it (even if by feel, we don't need to roll to hit) with a DC of 17 to end the effect. Additionally, you can upcast Dispel Magic using a 7th level slot to auto dispel it:
When you cast this spell using a spell slot of 4th level or higher, you automatically end the effects of a spell on the target if the spell's level is equal to or less than the level of the spell slot you used.
Dispel Magic wouldn't be necessary
You could save your spell slots and just deal any amount of damage to the invisible object to end the effect per the description of Sequester. The difficulty though is that you need to be within about 30 feet or so to use any of these solutions so you'd need a way to locate the sequestered object from afar still.
Closer look at why Sequester is not the target of see invisible/detect magic
I am fighting a monster immune to attacks from non-magical weapons that cannot be targeted by spells, I cast magic weapon on my sword and then hit the monster, do I deal damage to it?
Is the monster now the target of my magic weapon spell? I don't think so, as per the spells' description I can't target the monster with "Magic weapon" nor can I target an (in)visible object with "see invisibility".
I would deal damage just as I would see the Sequestered item.
I do understand the confusion and "Target" does need tighter usage and clarification in general, and Sequester's spell description could explain that targets become Immune to Divination magic or effects but that's not what it says.
can be hidden away, safe from detection for...
This doesn't say "detection magic" or spells, nor does it literally mean it cannot be detected entirely (you can still detect by touch for example).
It's fairly ambiguous as it is.