My challenge is usually communicating in-universe lore and setting details without sitting there for an hour talking, but my players are very good at finding creative solutions and work-arounds once they know something their characters would reasonably know.
My solution has been to write up information sheets with Homebrewery to make them look decent, so players have them for reference when needed, and can read them in advance when they feel like it. The first page covers things that the characters (or most NPCs) would know or have heard, and the page is marked as "rumor" because some of it may be downright false, but the characters wouldn't know that. Every player gets a copy of this page ASAP, and I encourage them to read it. I do 2-3 more pages after that, documenting ground truth of things (information key NPCs are hiding, secret curses on items, etc.) because I plan interesting twists and traps and like players to know I don't just make things up on the fly to be cruel.
Players get the rest of the info sheet as they uncover the truth themselves. I'd give it to them on a good Knowledge check or similar, but none of them have asked yet.
Example: Unique Item
I've got a homebrew campaign set in Middle-Earth, and the plot revolves around one of the lost rings of power. At the start of the campaign I give the Rumor sheet about the ring and a couple important NPCs. The Rumor sheet describes how the ring came to be in the area, how it ended up in the tomb it's said to be in, and the benefits the ring was supposed to provide.
If someone's foolish enough to put on the ring once they obtain it from the dungeon boss (and so far everyone's been keen to put it on ASAP, the turkeys), I immediately hand them the other page which explains the ring's curse. They were informed and with a Knowledge check or even just asking they could have learned enough to realize this ring was probably bad news.
Example: Homebrew Class
A player requested a shapeshifting power with specific abilities and limitations inspired by Game of Thrones. I obliged with the warning that there are vulnerabilities and limitations the player won't know in advance. She agreed, so I wrote up a 2-page info sheet. The first page described how the power works, when it can and cannot be used, and a bit of lore explaining why it's important that she keep her ability a secret even from other players. (It's fair, every player in this group has a secret ability, but they all think they're the only one!)
What this player hasn't seen is the second page, where the long-term costs of using her powers are detailed, her true origins (character has no memory of life before gaining powers), and true potential that won't be revealed until the character dies and cannot be revived by normal means.
The Shifter (mage) in the group should have gone to the magic store and bought some scrolls that might be useful. But the player of the Shifter isn't really aware that scrolls are a thing, and doesn't have all the spells memorized so wouldn't even know what spell scrolls to buy. As the GM, I know both of these things. How do I give that knowledge to the player without saying "You should go buy some scrolls of x, y, and z spells"?
With my approach, I'd prepare a simple info sheet describing the region and some common threats, casually including in-universe notes and quotes that suggest adventurers should have specific spell scrolls. Then I'd pressure the players, especially the Shifter, to read that info sheet before the session, and again at the start if they haven't.
If they don't, or still fail to prepare, that's on them. They know what their characters know.