A Mac Mini should be absolutely fine, no need for anything fancier. Second lowest baseline model /w 8GB RAM and 512GB SSD should be fine.
If you can, get a 16GB RAM model. And don't go for the 256GB SSD models because those will defenitely be too small in the longer run (system fills up and it's recommended to not use much more than 80% on an SSD, plus they gradually lose some capacity).
Over here, you can find the 2023 model with the 16/512 combination for around 800 2nd hand.
Note: For any typical daily life work, even 8GB of RAM will be sufficient. But who knows, maybe one day you would like to do some DAW stuff (which I'd recommend to any musician anyway). Or you'd like to get into video editing a bit more. After all, macOS comes with some things for free (Garageband but also iMovie), making it very easy to check these waters. So I'd tried to find something with 16GB RAM.
Fwiw, these new M-Macs are dealing with RAM *much* more efficiently (or rather "elegantly") than pretty much any other computer, so you possibly don't need much. The baseline Mac Mini has already been outperforming my old but still pretty powerful Mac Pro in all aspects, and we're talking more or less high end demands in terms of DAW work here.
Oh yes, there's some kind of "issues" with Macs and external non-Apple monitors (their onboard GPUs are completely tailored to work with Apple's own Retina displays), but in reality, these are absolute non-issues unless you're completely into graphics, video and possibly gaming. In case you're not, you can just connect any monitor. How do I know? Because apart from spending quite some bucks for the core machines, I'm connecting them to super-average monitors since decades. No issues at all.
