My experience is that I tried to use it years ago and it didn't work, so I continued using Signal. Straight up could not receive messages. That's probably fixed now but if I wanted to move away, I'd try SimpleX instead.
The work around did work however you needed to download an older archived version that was unpatched.
A small whiteboard on the fridge perhaps?
If you need to throw in the towel on email self-hosting, don't be ashamed. Mail servers are one of the more difficult projects to run. If you do end up outsourcing this, I recommend SendGrid, it's reliable and free.
You have to add the FUTO repo https://app.futo.org/fdroid/repo/
Sorting a music library is a very manual process. Your best bet is MusicBrainz Picard to clean up your metadata then use something like Lidarr and Lidarr Extended to maintain and continue to add to your library.
Cloudflare with CloudflareDDNS
I've used Joplin and Standard Notes. I do use Standard Notes premium and I much prefer it.
Gofile, Pixeldrain, Fileditch, Filen, Files.fm, Mediafire, Mega, MegaUp. I'm sure the list goes on.
I'm on Jellyseerr awaiting the day that Overseerr receives its decoupling update to allow Jellyfin servers.
You can selfhost Standard Notes. The notes are encrypted client side before they reach the server.