They’re gonna for sure drop the price on the 2020 Mac Mini after next week. But more significantly, for the same money you‘d be able to get the newer 2022 Mini that they’re expected to announce in less than 2 weeks that will have upgraded features. Again, Mac Studio is overkill.
As for the monitor, get whatever you like. The Mac Studio Monitor, IMO doesn’t blow me away relative to music making. Ok it’s got 6 speakers, but so what? You’d be using near field monitor speakers and headphones anyway. If you were a visuals professional (graphics, video editing etc) it would make more sense. If I were you, I’d just find a nicely spec’d monitor maybe bigger than 24” and go for it. I’ll soon replace my 24” for a 32”.