I use an HP mini PC - an Elitedesk 800 G5 DM with i5-9500 (6 core with 32gb ram), which is slightly smaller than a Mac Mini (well, the older Mac Minis). I also have a small stack of Mac Mini's ranging from Core2Duo to quad-core i7 to 8-core M1. I use all of them for music production.

Some mini PC's use "laptop hardware" meaning they use a lower power CPU and other parts, while some use the faster desktop parts. In my experience there are advantages and disadvantages to both - the more powerful stuff needs better cooling, meaning you'll more often hear the fans kicking in while the less powerful stuff would be near silent, but I also haven't really run into performance issues with the less powerful stuff, so that would be what I'd aim for. Look up the model of CPU both for benchmarks and to see how many watts it uses - the less watts used while offering good performance, the better.

For example, take a look at the chart here: https://www.cpubenchmark.net/compare/3444vs6112vs5852vs5719/Intel-i5-9500-vs-Intel-i7-14700T-vs-Intel-i7-14700-vs-Intel-i7-14700K

The leftmost one is my current CPU, which works great for music production. Even the lowest power of the current i7 chips is more than triple the speed. But look closely at the TDP row, that's how many watts of heat they can produce - and it's MUCH easier to cool a 35w CPU than a 125w monster. My previous machine used an i9-9900K which is only 95w, but it was difficult to keep quiet.

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