I would stick to the m series really any of them, if you go 2018 or back there won’t be support soon. No security patches. I have a 2018 and a m1. The 2018 only has like a year to a year and a half of patches. If you’re using it as a hub and not for inferencing locally, it doesn’t have to be all that powerful.

I would highly suggest checking back market. They have great prices for a little bit more powerful machines. You’ll have to look for Mac mini in the search bar because they don’t have a tab for it though.