I use their services since 2018 ! I can recommend !

DekuSMS adds encryption if your contact have it, and you can still use normal SMS if your contact doesn’t have the app installed.

https://f-droid.org/packages/com.afkanerd.deku/

There’s already this Megathread https://lemmy.ml/post/12432375

yes !

https://f-droid.org/en/packages/io.github.x0b.rcx/

https://rclone.org/ I use that to encrypt my files and send them to any WebDAV server, proton drive and others.