An interesting gadget to be sure! I was aware SIMs are writeable but unaware of this product.
If I understand the gist of it, you are or will be programming the eSIM profile from Manet Travel to this device using your Samsung Galaxy A11, then swapping it to your OnePlus 7 Pro for use.
For me, since I already have eSIM compatible phones and no devices with two physical SIM slots, the concept of a programmable SIM is interesting from a technical standpoint but not something I would have a need for.
Nevertheless, what you have found is indeed a solution worthy of MacGyver!