I don't use roaming, it's too expensive and makes no sense because I don't need phone calls or SMS when I'm abroad - online messengers can handle that without me overpaying. Instead I usually buy eSIM before the trip, for data only. Then on arrival I activate it and get online in minutes. So far my tried and tested are (Holafly - when I had to work remotely, so I picked unlimited data), Airalo and just recently tested
Ohayu, - I was the only one in my group who had internet in the mountains because they support more than one network and phone just switched to the strongest one.