Just a note - most LineageOS installs aren’t secure unless you re-lock the bootloader, as data can be extracted with some fairly standard mobile phone forensics kits. Unfortunately, not many devices support bootloader re-lock. The Google Pixel series is a notable exception.

Ideally, you would want a security hardened Android OS like GrapheneOS. Graphene only runs on Pixels as the development team specifically disallows it running on hardware with an unlocked bootloader for security reasons.

OnlyOffice has a lot of ties with Russia/CIS. I’d personally avoid it on that basis.

OnlyOffice has a lot of ties with Russia/CIS. I’d personally avoid it on that basis.