Slightly tangential but I'm wondering how hard would it be to build a “bring your own eSIM” kind of service that you can register an external SIM profile QR cod

Slightly tangential but I'm wondering how hard would it be to build a “bring your own eSIM” kind of service that you can register an external SIM profile QR code with and it would host it with a SIP interface for voice + some kind of API for SMS, and allow you to switch active line between different SIM profiles on the go. (Charge something like 10 ¢/mo per profile stored, and $5/mo per active line?)