I have a P4 CM, for which I have:
- Installed a 2TB NVMe m.2 SSD (with a PCI to m.2 adapter)
- Configured Samba and use it as a poor man's NAS, which is actually not so bad.
- Installed Kodi and hook it to TV via HDMI 0, another poor man's media center (as a side effect, YouTube plugin for Kodi doesn't have ads)
- Installed Syncthing, which servs as my major private backup system. (I know, Syncthing is not really a backup solution per se, but I just enjoy the dropbox-like convenience so much, and it has some basic versioning capability, good enough for my need)
- Installed PiHole (actually on another Pi 3 which I have for years and reluctant to throw away as it's still working) and my kid won't be annoyed by the ads while playing with iPad - I'm diverging, but some app still shows a "watch videos for in-game items" button even after I purchased the "remove-ad package", which I really hate for kid to waste time on, not to mention many App Store games/apps are heavily ad-ridden nowadays)
- Occasionally run the free Mathimatica that comes with the system for some very basic math calculation/demo
- Setup nginx and configured a DDNS with LetsEncrypt, it serves some very basic stuffs that I'd rather keep private.
- Used to run some cron jobs for some minor tasks.
In short, it's a low-power tiny linux server which I'm satified to tinker with, and I assume other good SBCs like BananaPi/ODroid/etc will serve the same perpose well also.
Sounds almost exactly like the use case that I bought my Pi 4 for, over a year ago. Sadly it's getting replaced today with a MeLE Quieter3Q. There were too many things that didn't work properly on the Pi. Wine (because ARM), YouTube crashes in chromium and most videos have no sound in Firefox. Boot issues if you have a USB drive plugged in. No power save. The MeLE is a SBC with a Jasper Lake CPU, 8GB memory and built-in 128gb of storage on eMMC. And an M2 slot. And a case. And a power supply. And they're actually in stock. It feels more like a 'real computer' then the Pi. It's a lot less work and probably costs the same when you factor in all the crap you have to buy for the Pi.
In short, it's a low-power tiny linux server which I'm satified to tinker with, and I assume other good SBCs like BananaPi/ODroid/etc will serve the same perpose well also.