Can I install 2 eSim on an iPhone 11?

You can install multiple ones, but only one is active at the time (or at least I can't get multiple sims to work in parallel).

what works flawlessly for me is having a physical and a sim in parallel (i.e. being able to receive calls / data on both in parallel. but for thew sims, when I toggle on one, the other one gets deactivated automatically (iPhone 11 Pro)

You can install a second eSIM on your iPhone 11, however, you can only have 1 Physical SIM and 1 eSIM active at the same time. On an iPhone 11, you cannot have 2 eSIMs active at the same time.

I recommend that you continue to use the eSIM (Mint Mobile) from US and once you get to Europe, then get a physical SIM card for the EU data plan. This setup will work well.

Axel F.