Hey man don't give up! Well maybe give up on using the mac mini - i've never used one but if it's going to be a pain to install linux go grab something cheap on eBay or FB Marketplace if that's a thing in your area. I recently bought a cheap dell optiplex (I think?) on marketplace for like, ~$25? Not sure what your use case is, but if you don't need a super fast nas, most cheap desktop machines on your local buy/swap community purchase place will do the job just fine. Don't let the mac mini be what holds ya back!