I'm running a pi 4 with 4GB RAM, a quality power supply and a fan as a desktop. It is hooked up to a 23" monitor running on an SDD. It is more reliable than my older iMac (2013). And yes, you need a quality power supply, but it has been rock solid for me as well as being dirt cheap.

I also have a PI 3 taped underneath the table for simple utilities and I forget it is there because it "just works" - for the last year.