MGG #815 - Walter
@DaveHamilton - In regards to Walter's question about the 128 GB SSD, instead of moving the home folder, I would recommend a better solution being making the external drive bootable. I actually do run with my Home folder being relocated to an external 1TB SSD. The main challenge here is that I *cannot* enable FileVault on the external drive. This is because the key for the external drive is not loaded in time and the drive is not readable at login. Gives some ugly & scary errors !! I needed to make a plethora of encrypted sparse bundles to protect my precious goodies.
That said, even if you make the "always connected" external drive bootable and the main boot drive, be sure that the internal storage also remains bootable with a valid admin account and home folder.....this is to deal with issues that can/will happen down the road if that external dies or becomes disconnected.
And lastly - do not forget to enable the booting from external settings change, since I am guessing this Mac mini is the 2018/T2 kind.