I use an LG V30. Works great in Canada, only text and data in USA and unknown for Mexico. Thinking of buying a Pixel 7 pro, but I know pixel phones don't have any calling yet in USA, even though they are VoLTE capable. I hope that changes.
You can see list of VoLTE compatible phones here:
VoLTE capable devices - Member Forum (lum.ca)
I doubt LG V30 will work in the USA. You might be able to get VoLTE enabled in some cases in Canada. I currently use a Pixel 6 Pro. It works fine in Canada but cannot use in USA for Calling. SaskTel never sold the Pixel phones officially for whatever reason, that could be the reason for not being fully supported. Even in Canada, the Pixel doesn't have VoLTE on Lum.
My V30 has working Text and data in US, but no, the VoLTE voice calling doesn't work. Discovered that on my last trip in April. Driving in Los Angeles would have been a nightmare without the data, I'm very happy it worked! As a result, the driving in LA turned out to be one of the most fun parts of the trip!
I started with a Samsung S10 without VoLTE and that caused see some initial (solvable) concerns in the US to enable voice calls. Data worked great in about 15bstates we travelled through travelling from Canada to Southern California and back. Unfortunately that phone didn't like to swim in Maui 🤦♂️ so I now have a Samsung S23. It works seamlessly in continental US (mid west states, MT, ND, MN, WI so far), it hasn't been to Mexico or Hawaii yet so can't comment on those.
I’ve been in Mesa, Arizona (greater Phoenix) since mid October.
My wife and I are both with LUM.
My wife has a Samsung A14 5G. As soon as we crossed the border it synced with AT&T and has worked pretty much flawlessly – calls, text and LTE speed data. It worked in Montana, Colorado, New Mexico and now Arizona. Not so great in Wyoming.
I have a Samsung A12. It is a 4G phone, and works well in Canada. However, when we got to the US, it cannot see the AT&T network. It does see T-mobile, and will register with T-mobile, but calls are poor and data is literally 2G speed (T-Mobile Edge network). The 2G data is pretty much useless.
So I bought an unlocked Samsung A14 5G (same as my wife’s) and copied everything from my A12 to my A14. And it finds AT&T and now my data is at LTE speeds – and calls and texts are good.