Don't all sim cards (after they've been activated) work anywhere?
As long as you have the right amount of EUR topped-up it shouldn't be a problem (with the EU's roaming laws).
"As of 2021, the following countries do not have mandatory SIM card registration laws: Bahamas, Bosnia and Herzegovina, Cabo Verde, Canada, Chile, Comoros,
Croatia, Czech Republic, Denmark, Estonia, Finland, Hong Kong,
Iceland, Ireland, Israel, Kiribati,
Latvia, Liechtenstein, Lithuania, Marshall Islands, Micronesia, Moldova, Nauru,
The Netherlands, New Zealand, Nicaragua,
Portugal,
Romania, Samoa,
Serbia, Slovenia, Solomon Islands,
Sweden, United Kingdom, United States of America, Vanuatu. SOURCE:
GSMA (pgs. 54-61)."
Source:
Timeline of SIM Card Registration Laws
I have highlighted most of the EU/European countries in the list, so these should work in theory I assume.