I have a 10" width rack cabinet where my Proxmox cluster (three mini Lenovo Thinkcentre) lives. I’m currently designing a 10" mount to hold an old phone so that I can see my server monitoring/status through the glass of the door.
3D printing is great for stuff like that.
Everyone else has described the complications that a Mac mini would have. So why not consider something else? Lenovo, HP, and Dell make 1l ultra small form factor PCs and they’re pretty cheap on eBay. They’re also low power. Search for Tiny Mini Micro to find information.
I have three Lenovo Thinkcentre machines - two with 32gb RAM and one with 64gb RAM - running my Proxmox VE cluster. Highly recommend using those small machines instead of a Mac mini.