You need a wifi that doesn’t have a log in page. Which might be challenging while you’re traveling. Maybe a friend’s house?
Or (silly me) a travel router would work. I used one on a trip to Thailand. Set up the travel router to connect to the hotel’s signal and log in using the name/room password thing. Then I used the travel router to set up my same network SSID and password from home, so that my Sonos would “just work”. Slightly different for setting up a Roam, but at least you then have a network to log in to that doesn’t require a login page.
You could also set up the Roam using two phones. Use one for it's wifi and the other for setting up the Roam. You might need to reset the Roam on coming home (two households) but at least you can use it with bluetooth while you are on the road.