You'll need a travelling eSIM for that as plans from regular providers usually have restrictions on how long you can use them in roaming. The downside to this is that travelling eSIMs usually don't give you as much data as some local plans - at least in some markets.
Agree but despite the roaming at times it can be way cheaper. For instance paying for BElgium operator (not necessarily the cheapest) you can buy an unlimited 5G (limited to 90G in BE without throttle) which in roaming is 31G costing 25 Eur.
I’ve also seen some cheaper providers than this in DE but they limit 5G to 50mbps :(