Turns out, my iPhone, which I decidedly bought for its dual SIM support, is worthless as a brick.
While my carriers support eSIM, it turns out, that they support industry standard eSIM, and Apple cooked its own thing, which they don't support, and which requires each and every carrier to negotiate with Apple.
As a result, expect serious anti-competitive results: carriers may have to pay Apple to offer eSIM support for iPhones, as a result carriers will very likely restrict which plans they offer to iPhone users. The ability of just getting a SIM/eSIM without restrictions is over, now Apple and the carriers will tell you, which plans they allow on an iPhone, and which they do not.
No more walking into a store without a device, getting a SIM for whatever plan you want, and sticking it into the iPhone. No more walking into a strore, getting an eSIM card with QR code, and simply scanning it on your iPhone. No, you'll need an Apple specific eSIM. And who knows, next they drop physical SIMs altogether, or come up with proprietary SIM cards, which also only work with Apple.
This means, e.g. no possibility of getting say GooglFi on your iPhone, as Google will not support Apple's eSIM, even though of course they do support eSIM. That's how restriction of choice starts. When the next phones drop all physical SIM slots, we and the carriers will be held hostage by Apple. I hope the EU anti-trust authorities are on that like flies on ****.
I now fully understand why the mobile industry was so opposed to Apple's SIM ambitions: it is NOT that they fear competition, they don't want Apple as gatekeeper between them and their customers, which Apple is forcing onto them by going a proprietary route.
It is also misleading that Apple doesn't disclose on its product pages, that the eSIM in question is not in any way standard compliant, but a totally proprietary thing. Customers are led to believe, any carrier, which supports eSIM, would work. Far from it, each and every carrier will need to negotiate with Apple.
Hats off to the Chinese for not bowing to that nonsense.
Where can I swap my iPhone against a Chinese model?