Swype by Yallo is the eSIM I've used.

My Telecom Italia SIM ran out of roaming data while I was in Switzerland, and there was no way to top up. Swype had a first month free promo, so I signed up from my Airbnb. I did have to send a photo of my documents, but the total time from download to data was less than 30m.

I took a quick (1 week) work trip to Germany this summer. I was trying to figure out how to get a SIM before getting on the train, when I remembered I still had the eSIM in my phone. I downloaded the app and bought data - $15 per month + $3 per day (since I was roaming). Not only was it super convenient, but I had unlimited data with roaming. I don't think even local cards get you that.

For short trips to Europe, I definitely recommend Swype for its convenience.

Depends on the country. UK has no national identity cards, you can buy a (prepay) SIM in the supermarket and pay cash if you like.

Here in Latvia you can buy sims from all major providers without any ID for as low as 0.99€. The caveat is that you have to top up them regularly because they have expiry times depending on the amount you top them up.

Depends, I think you can get them in Tesco pretty easily, and the MVNO I was talking about was giving numbers for their data plan from the UK, but with roaming all over Europe.

I think it's more difficult in Germany than a lot of other countries.

In France, providers will require you to provide KYC information within 14-30 days of obtaining the SIM, or it will be deactivated. Suitable for a short-term travel use case.

In Sweden there are usually stands where you can pick up sims for free, in airport outside shops etc.