What made you choose Nebula over Tailscale? I'm running it through a self-hosted Headscale server and it's working well so far. I haven't looked into Nebula too much.
I started self-hosting a music server locally on a Raspberry Pi long before I switched careers to go into IT. I actually learned a lot that way.
Another approach to webapps in Firefox is to create separate browser profiles and create shortcuts for them.
Don't you have to download episodes to your server first in ABS? That makes it useless for me as a podcast app.
I recently switched from etesync to a self-hosted solution and didn't want to install a full Nextcloud on my tiny home server just for that. So I initally tried out radicale as well, but I didn't like the default user handling (no authentication at all) and the project had been unmaintained until very recently (two weeks ago). I switched to baikal then and I am quite happy with it so far.
To be honest, I would advise against opening your home network like that at all. A VPN would be much safer. If you use something like Tailscale it would be much easier as well and doesn't need opening any ports at all.
Apart from the dependency stuff, what you need to migrate when you use docker-compose is just a text file and the volumes that hold the data. No full VMs that contain entire systems because all that stuff is just recreated automatically in seconds on the new machine.
Signal notifications work fine without GCM, and even Whatsapp does to an extent
Oh, so that's why there's no hint of UP in the UP version of Molly
I think you can create a custom iso like that with CoreOS, not something I'm super familiar with though. You can have a look at this:
https://docs.fedoraproject.org/en-US/fedora-coreos/live-booting/
Also Sam Altman is a grifter who gives people in need small amounts of monopoly money to get their biometric data
+1 for AirMusic. I use it for my snapcast multi-room streaming setup.