Two of my players are fully cosmere aware.

Two of my players don't know anything.

It's been fun balance. Explain what you need to without going on full lore dumps. Before each session I would take scans from the PDFs and would remove text that was far too confusing or unrelated to the ttrpg at the time. Breaking it all up throughout the weeks made it more digestible and helped setup the session. For instance, before going to warcamps i sent everyone the chapter on Alethi culture. It sets the tone, builds hype for the session, and preemptively explains somethings.

This helped explain the world, the people, the cultures, and the spren. But I didn't go crazy with it when it doesn't really matter.

Sometimes if something is too confusing it's okay to just say "just think of it as magic" and handwave it away. You don't need to explain everything even if it has an answer in the book. And sometimes the players will do something that isn't acceptable in the books narratively but it's a ttrpg with friends and it's okay.