Thunderbolt is Intel Not Apple; they just use it under licence. (Most PCs these days have a header that you plug a card in (For little money) if you need Thunderbolt speeds)
Running Software (Or even the OS) on an external drive has been available on Pcs (Personal Computers) for donkeys' years, whether they run Mac, Windows or Linux.
Nvme drives are used in most computers these days and easily match the speed of the drives in Apple Silicon Macs, but at a fraction of the price. (Many are even faster)
As I said, the Mac Mini is a great computer, and if you want the Mac eco system it is the best value out there.
BTW: there is no one OS that is best for everything, for that you need Mac, Windows and Linux to take full advantage of what's out there.
BTW: even basic computers these days would make your 2011 Mac look like a dinosaur, so it's hardly surprising you are blown away by the new Mac Mini.

Bill