For most functionality on Android, you also need to be signed in with Google
Really? Funny, my Lineage devices have zero Google Crap and they work just fine. Phone, email, SMS, messengers (Telegram, XMPP, Wire, SimpleX, Signal), web works fine, I’m able to run my sync tools like Foldersync, Syncthing, Resilio, my calendar works, my shopping list app works and syncs to their servers just fine, I use 4 mapping apps two are offroad/hiking, same ones I used when it had google) my address book works, etc.
I have ~300 apps on my phone.
So what’s this “most functionality” thing that I apparently don’t know about?