I've only been committed to a UT daily driver for a couple of weeks but I'm not looking back. Running a Pixel 3a XL.
On T-Mobile and coverage for my area is good.
Mobile data is good and Hotspot works well.
GPS navigation is working great.
Use telegram mostly but SMS is good and MMS is working.
Calls are fine, phone connection and call-through vehicle work great.
Even Spotify (Futify) is working well.
The E-Book reader is awesome and pdf's read well.
Asteroids and Pacman, I'm covered.
The only other things I would use if remedied are speakerphone calls and calls with headphone mic's, be they wired or Bluetooth. But even without these, I'm 100% on UT.

I am ready to pull the plug on my Verizon phone, I don't pack it anymore, but I'm going to wait and see how the T-Mobile network changes affect coverage in my area come January. If all goes well I will be setting up phones for the rest of the family to move them off Android after that.

@rik I appreciate the heads up. I'm not picky on the carrier at this point. I'll look into T-Mobile in my area. Thanks a bunch.

@thousandtopics Yeah, I wish I could have gotten out cheaper but I need hot spot and unlimited data for work and kids for On-Call work and kids doing remote schooling sometimes. It's working out very well.

@rik Success!!! Thank you so much. It was odd though. It didn't work at first, so I drove into town and tried where I knew I would have the best signal, and still nothing. I came home and deleted the failed attempts and then tried again and it sent and received pictures just fine.

The settings are holding just fine after reboots.

@rik It's been working great all day today, and it's getting pictures just as fast as my S9 on Verizon. Thank you again! Turning off the WIFI is a bit of an inconvenience but at this point, I really don't mind it as I don't want it connecting to any insecure WIFI along the way, so I was already turning it off when leaving the house. If there is ever anything I can be of help with testing on a Pixel 3a XL, shoot it my way, I'd be happy to help.

I flashed another Pixel 3a XL this morning for a friend that I got interested in this, cause flashing misery loves company right? LOL He tried for two days but could not get Google Play Services to flash the phone back to 9.0.0 (PQ3B.190801.002, Aug 2019). I tried this morning and couldn't get it to work either, so I resorted to doing it manually and it went off without a hitch. Here is what I did. And just for the record, I'm on Linux, Ubuntu to be exact. You should have ADB and fastboot installed on your computer.

Go to the Google play services site and instead of "Flash" click on "Link" next to the 9.0.0 (PQ3B.190801.002, Aug 2019) image. It will download the zip. Unzip it and cd into it in a terminal.

Start with the phone unlocked and on in a regular operational state with developer mode and USB debugging enabled. Bounce (turn off and on) USB debugging so you get the pop-up to always allow from this computer.

In the terminal and run "adb devices" to make sure you can see it. then run "adb reboot-bootloader" which will take you to the fastboot screen.

The "Flash-all.sh" script from the zip you downloaded will fail, at least it always did for me, due to the "if" statement at the beginning. Instead, cat the script and just run the fastboot commands in it manually. There are only a few to run and remember you have to be in the directory these files are in to run the commands. This worked on two phones so far. I then ran the 0.8.8 installer and like magic, it was done. Like anything else in Linux, there are several ways to do anything and you never know when you might have to do something different for some unknown reason. I believe in picking up these referb phones, there is just no telling the how's or why's in which they were wiped and what it will take to get them to flash. But here's yet another way.