Yes, what ever has synced, when you go offline it will still be there, when you reply/like/quote notes, they sit there, once back online everything gets push to your relays.

Pretty nifty. I was on a 12 hour flight had “nostr” all the time, I was replying to messages and all. But a glitch (reported) stopped them from being broadcasted.

But that’s the whole idea. Pretty cool.