Not that the functionality does not exist (p2p, literally) but if my grandma cant receive the family pictures its not basic.
What about encrypted messaging apps? Maybe your grandma can’t figure out Signal, but she could probably work out how to use WhatsApp (which uses the same encryption protocol) given how popular it is in some countries.
I’m not saying you have to self-host… You could still use something that’s open-source and remotely hosted.
Sentry (error logging and bug reporting system) is like this for example. They have a hosted plan, including a generous free plan for open-source projects, but Sentry itself is open-source.