I'm going to Norway in the new year - first trip abroad ever! I've got EE's roaming at £2.40-something per day, but I've also got one of those travel eSIMs, from something called Breeze (because it came free with travel insurance, £12 of data free with £6 of insurance, go figure). The latter seems to show up as 3 AT in the UK, weirdly.
Hopefully one or the other, or both, will work when I get there. I've got anxious visions of landing hundreds of miles from home and having no way of accessing tickets, emails, car hire booking confirmations, etc.
Take a Three PAYG SIM or a smarty SIM with you.
Have a great time, I've never been to Norway myself but it's very much on my bucketlist
These roaming SIMs usually have a roaming broker, 3 AT is very common. Tele2 SE is another common one (Spusu use Tele2 as a broker for their EU roaming).
The broker works by 'selling' their roaming agreements as a service to other networks/providers. That way, smaller 'full' MVNOs like Sky, Spusu, Lyca can have their own roaming agreements. These brokers also work with eSIM companies.
The downside to this is, especially when an MVNO uses a roaming broker, your traffic gets routed back to the broker and then back to the UK. So ping times go sky high - and especially further away, doing anything can be a chore.
Spusu is a great example of this. I was getting ~30ms pings in France whilst roaming on iD (iD use Threes roaming agreements and not a broker, a direct connection back to the UK). Spusu was giving ~150ms pings as it was jumping to Sweden and then back to the UK.
An even worse example, from my recent US trip, was Honest Smart SIM. Their roaming broker is Proximus & TIM IT (depending on whatever it feels like it seems).
Whilst using TIM IT, the pings were 500/600ms, as traffic was going back over the Atlantic to Italy, then back to the UK.
My Three PAYG SIM, was again a direct link back to the UK, 90ms ping.