I went with Debian and I use Docker for containers. I considered Proxmox, but I didn’t end up trying it. PiHole is a good application for the Pi Zero (I have an early generation Pi dedicated to running PiHole), but you could also run it on the Beelink.

I strongly recommend you download Obsidian and keep hyperlinked notes on everything you do and links to every tutorial/resource you end up using.
Have a place to keep all the passwords your services will end up needing. A password manager is the best option. Make the password on your admin account on Debian (or whatever) easy to remember and enter, since you’ll need to sudo a lot.
If the Beelink comes with a copy of Windows installed, you can recover the key from within Linux with the following command:
sudo strings /sys/firmware/acpi/tables/MSDM
Then you have a spare Windows key should you ever need one.

Sears & Roebuck

AWS

According to my Synology:

Where are you finding this data? It’s not Info Center -> Storage…

I use Portainer mainly to start / stop / restart containers without the mental load of using the command line. It works fine with Compose if you can get (or write) a yaml file for the container you’re interested in, or you can use it to pull from the repository and set everything up if you can’t. Portainer also gives you a nice, one-stop view of the current state of your containers. Basically, it can’t hurt to have it around.
Personally, my favorite Docker management GUI is the one that comes with Synology NASes. It’s much less clunky that Portainer and iirc a little more powerful. But of course it only runs in their hardware.

That’s good to know. I leave location services off on Android when I’m not using them and the possibility of a triangulation leak always nagged me a little. Not a lot, because I’ve never heard of any actual harm coming from it. But a little.

Well that’s a shame. I’m sort of half-assedly using syncthing to backup my photos from my phone to my server, but mostly I rely on immich. I never really got the hang of using syncthing with my phone.

Masochism, paranoia.

Another vote for Debian, and I’ll suggest you go ahead and install Jellyfin directly rather than messing with Docker.
https://jellyfin.org/downloads/server
I’d been running JF under Docker on my NAS, but when I moved to a new server I decided to just install it directly and it hasn’t been any problem at all. You’ll get a notification when it needs to be updated and it’s just a few clicks to do so. You won’t have to fight with Docker to get hardware acceleration working - which isn’t to say it won’t be a PITA, but it’s one less layer of complication.