it has different layout but I don’t know if you can quickly switch between layouts

I can’t help with installing lineage os apps but I can suggest unexpected keyboard. I tried a lot of foss keyboards and this was the best in what I tried. It has a lot of customisation You can basically change anything. I even added my own keyboard layout to it.

try koreader I’ve tried a few e-book readers this is the best one I found so far I think it’s available in fdroid

Bitwarden an open source, simple password manager it does it’s job very well