Looks like this is not a new thing, it would be nice to have a more unified experience across the EU (Just like https://eduroam.org), but I wonder if it would be more useful to have a unified minimum data cap on mobile networks instead of building out WiFi coverage across cities?
That said, now that many phones support dual-SIM, I do wish there was a low-friction way to connect to a local 5G network without downloading an eSIM profile and all that.
I haven’t really had much signal problem and I’m not travelling through particularly built up areas (on the New York to Miami train, nearing the GA/FL border)
On most trains I've traveled on, Wi-Fi (if available) also works much better since the antenna for that is usually on top of the train, and windows are sometimes coated with a metallic paint to keep out solar radiation.
In the EU there are no roaming costs so it's not any different when travelling.
Besides that, neither tethering (for reasons other than cost, mentioned above) nor international roaming (increased latency) are a perfect replacement for fast local Wi-Fi at this point.
(also: increased latency for roaming?)
So yes, Eduroam is no different than roaming on any 4G/5G network, but it's also not worse. If anything, I trust the backend security of Eduroam providers more than I trust mobile carriers.