Besides raspberry PIs, I am a big fan of intel NUC running docker.
The host OS of my intel NUC is CentOS Stream ( = 64 bit Linux version maintained by Red Hat - but I guess ubuntu would work as well).
The intel NUC I am using is a low end version with CPU = Intel Celeron J3455 (4 Threads)
Its performance is really ok and at the same time doesn't consume much electricity which I find important as it is running 24x7.
My NUC has 6 GB of RAM which is 6 times more than my pis and which is very interesting if you want to run multiple docker containers.
FYI I am running 34 docker containers for months without a problem and still have 1.7 GB of RAM available (of course memory consumption depends on the type of container - FYI my node-red containers consume between 70 and 200 MB of RAM depending on the actual flows)
If you want sufficient reliably storage you can put an SSD in it.
You can also save a few bucks by looking for a second hand version.
I have bought mine around 140 euros with memory and SSD included.
It doesn't have all those IO pins a raspberry pi have but my NUC has following hardware/ports
- infrared sensor
- hdmi
- bluetooth
- 4 x USB 3.2
- built in microphone
- digital audio output (S/PDIF)
- Gigabit ethernet
