+1 for XMPP
I’m currently using a public server until I get my own (Raspberry Pi based) Prosody server running
Never had a missed notification / message and video calls are great too… even Grandma can use it
Using Conversations (Android) and Monal (ios)
I moved from Backblaze to a Hetzner storagebox, to backup my Arch (btw) NAS.
Simpler to work with and cheaper.