Jim, I understand your reluctance to try a SIM card again, but it might be easier this time. In Italy, SIM cards must be registered with your passport etc, so usually you have to go to a mobile store. In the UK, they don't have to be registered - you can buy them at a grocery store or even a convenience store. They don't cost much. If you try one and it doesn't work, you've wasted maybe $10 or something but you try it at our hotel, not waste two hours at a mobile store.
Plus a modern Pixel phone is I'd guess more likely to work with a UK SIM than some older Verizon phone that was CDMA-based but had to roam on GSM in Europe.
Here's some info on UK SIM cards if you want to learn more:
https://prepaid-data-sim-card.fandom.com/wiki/United_Kingdom
An eSIM might be an option as well.
I highly recommend Google Voice too - you can make unlimited voice calls even to landlines through the Google Voice app, though as with WhatsApp you need mobile data or WiFi to make that work. For this Google gives you another (free) US phone number to use with the Google Voice app. In the old days, Google was picky about prepaid calling plans and would not allow you to use the service or get a phone number with one. I haven't tried getting a new Google Voice number for a few years now - it's worth trying now to see if it works. Nothing to lose if it doesn't. If you can get a Google number now through Google Voice, you can use it in Europe with WiFi or mobile data for calling and texting. I use Google Voice the US for most of my calling and texting anyway, so when I go to Europe and use my Dutch Vodaphone SIM there, my calling and texting wok the same as at home.