I have the 256kbps Free Roaming service on all my lines. I find it a great place to start when arriving at a new roaming location. It seems to be more than twice as fast as the basic 128k, and I wonder if part of the bandwidth is used for "Housekeeping" and unavailable for data service?

I travel with an iPhone 13 Pro Max, iPad Mini 5, and iPad Pro 11", all of which are esim capable. Typiclally an esim service like Airalo ends up on the Mini 5, which is my daily out & about device while exploring. Great for mapping and browsing, and fits in a back pocket of my pants when walking and not needed. Hotspot is permitted on Airalo, so that is used for service on my phone, and by my wife or others I may travel with. With the Airalo WiFi connection, we can all also make free calls to and from the US on our T-Mobile cell service while sightseeing. Everything but the Airalo device can be on WiFi only service, and have good connectivity and no fear of roaming charges from US calls.