Thanks for the leads.
I live in Upstate NY where there are cellular dead spots larger than some European countries. I'd feel like a chump if I paid for an expensive cellular plan which doesn't work where I live or where I drive on the weekend. There is WiFi at home, I'm about to set up WiFi in my rental house, my wife wouldn't mind setting it up in the barn, WiFi works at work, WiFi works at every gas station, on the bus, etc.
(To be fair my son has an Android Go phone with AT&T prepaid and that sends calls over WiFi when it has to, plus it comes up as a real mobile number so you can use it to register for WhatsApp, dating sites, and things like that.)
Overall I have no complaints about the quality of Skype-POTS calls, they aren't any worse than cellular calls (how the hell can a salesman spend all day talking on a cell without having their neck knot up from the stress of listening closely through a bad connection?) It's the other aspects of the UI that drive me nuts (particularly the calls that I can't hang up on)
My take is Google comms products are decidedly inferior to competitors when your connection isn't the best. On my DSL at home I have a reasonable experience w/ Skype, Zoom, Go2Meeting, Discord and Slack but every time I try Google Meet or any of the other 1357 me-too products from Google people ask me "Is your internet connection really that bad?" It makes me really feel excluded.
I did take a look at Twilio but it came across as more of a construction set for voice applications and not a softphone for general use though I guess I could build or find that application. Building something big with Twilio looks like it would be a lot of fun though.