The proton suite or consider murena.io

Murena is the company behind e/os which is a privacy (from big tech) driven android spin. Whether or not you want to flash your phone with the os, you can use their cloud suite for a few dollars a month. It’s built on nextcloud, has email, calendar, notes, picture and file backup, productivity suite…

Murena isn’t end to end encrypted like proton, so it depends on your threat model I guess