I’ve always backed up my SMS to my E-Mail inbox. With something like SMS Gate or SMS Backup+. I think it’s nice to have all messages in my mail program. Of course that only does one way. To reply and get immediate notifications, I use KDEConnect (or GSConnect which is the same thing for GNOME.)
By the way, you can still run the Yunohost installer ontop of your Debian install… If you want to… It’s Debian-based anyway so it doesn’t really matter if you use its own install media or use the script on an existing Debian install. Though I feel like adding: If you’re looking for Docker… Yunohost might not be your best choice. It’s made to take control itself and it doesn’t use containers. Of course you can circumvent that and add Docker containers nonetheless… But that isn’t really the point and you’d end up dealing with the underlying Debian and just making it more complicated.
It is a very good solution if you don’t want to deal with the CLI. But it stops being useful once you want too much customization, or unpackaged apps. At least that’s my experience. But that’s kind of always the case. Simpler and more things automatically and pre-configured, means less customizability (or more effort to actually customize it).