I personally love my pi 4 as a media server, it is capable of running jellyfin and navidrome just fine.

I also use it for klipper for 3d printing, I don't know if that is something relevant to you.

It’s easy to set it up as a mobile “off-grid” wifi access point to host a calibre library of banned books.
https://github.com/hydroponictrash/Tiny-Banned-Book-Library

I have mine running NextCloud for syncing files between Android & my computer.

the nextcloud android client isn't the best when it comes to automatically syncing... I've read that one should use Syncthing for function syncing, but haven't set up that.

I'm running a triple boot using PINN with:

• Lakka - For retro gaming of old platforms (GBA, PS1 work great)
• LibreElect - For KODI
• PiOS Lite based on bullseye which automatically boots to a user and starts steamlink so I can play there with my stronger desktop computer.

My website nx2.site and my Matrix server matrix.nx2.site runs entirely on a RPi4-2GB

The Pi 4 is my go-to machine for sound installations. Where the 3B was just too short on memory (I run mostly on JVM which can be demanding). You also have headroom to create a big RAM disk, which can speed up processes quite a bit. The plenty of USB ports means you can easily connect sound interfaces, external harddrives etc., or plug-in a Pico if need to outsource some sensor code to a micro controller.

an hour of commandline fiddling

This is of course if you are not familiar with it. I guess the Pi 4 appeals a lot to linux users, like myself, because I don't even have to think about most things I do on the command line, as they are essentially the same as on my desktop laptop. Logging in via VNC makes it just another computer that works exactly like the other computer. So yes, learning curve is there, but then it becomes second nature; been using them for four years now (3B and 4B).