That doesn't allow you to have all of them active at the same time. You can already store multiple eSIMs in newer Pixel and iPhones (you just cannot use more than two SIMs/eSIMs at a time).

Stored SIMs/eSIMs is not the same as active SIMs/eSIMs.

Oh true I glossed over that part... Although tbh I don't understand the use case.

i'm surprised this works, in the sense that there aren't tons of technical safeguards and/or lawsuits getting in the way of someone doing this