esim.me, 9esim and "sysmocom eUICC for eSIM" are eSIMs in the SIM card form factor that you can load the SIM profiles onto and use them in any device with a SIM card slot (and of course transfer between devices). In my opinion, that's the best of both worlds.

It's good, but they're expensive as fuck for what they are.

The best option would be a software-only eSIM with full transfer support, IMO. But we don't have that, because GSMA says we can't have nice things.