Converting a physical SIM to an eSim in an Apple iPhone 16

[biscuits99]

I've put my physical nano SIM from my old phone in a new iPhone 16 with iOS 18.

This is all working fine without issue.

I then tried the "Convert to eSIM" in the iPhone 16 settings, but this fails with this error:

So I was wondering if anyone else had tries this convert process, or if I need to request a QR code from an O2 store instead (which I guess I add via the "Add eSIM" option on the phone)?

That said, I've just read a few people here struggling with eSIMs so I'm wondering if I'm better off sticking with a physical SIM and ask that no-one steals my phone and takes the SIM out?