Switching between eSIMs on the same phone is very easy. But migrating the profile to another phone is somewhat complicated in my experience. Nothing you would want to do regularily in my opinion. Essentially you have to disable your old eSIM and create and then provision a new one. Some plans allow you to have multiple SIMs activated at the same time. But usually you have to pay extra for that.

As I remember, they just gave me a piece of paper with a QR code, I scanned it with my phone and here I have an esim. Are you saying eSim is now locked to my phone and if I scan the same paper with another phone it won't work?

The QR code contains a one time use code, used to authenticate with the LPA server and lets you to download the SIM profile from your carrier. Once scanned and eSIM installed, the QR code is no longer valid. The carrier must re-issue a new QR code for that SIM to allow you to load it on a different device.

That is how it works with my operator. Once the eSIM is activated, it's tied to the phone. But I'm not ruling out it's possible to make the QR code "reusable".

Getting a new eSIM is not terribly complicated. But you have to log in, click through some menues, wait for an SMS code and an email to arrive, wait a couple of minutes.

Agree switching devices is still a pain point with eSIM, but solvable by the telecoms and a push by Apple to eSIM only devices will speed this improvement.