Thanks, I don't know if I understand enough about these options even to ask informed questions, such as: how much does it matter whether we're getting data by Wi-Fi or cellular service. I understand that Google Voice, which we'd use only for emergencies, requires Wi-Fi. Does Google Fi count as Wi-Fi? If I search for Pocket Wifi on Amazon or wherever, are there features I should look for?

On this trip we ordered https://hippocketwifi.com/en/ from France; we've been in the house more than we'd like, with my wife being unwell, and quickly their 1GB/day plan wasn't enough; we upgraded to unlimited. For the next trip it's tempting to use them again and not worry; they can ship the device to us in the U.S. , and have 28 days of unlimited data for around 200 euros. Another tourist-based service, in Italy, is https://www.witourist.com , but their pickup options may not be so convenient to us.

We have all Apple devices; my iPhone 8+ appears not to be listed with eSIM, and I regularly put an Italian SIM in it. I think my wife's 12 will still be locked to AT&T for a while.