Just an update. I haven't really been able to find that much on Halium 12 and the Google Pixel 3a. Perhaps a mainline Linux build would be better? However, it looks like we may have some bad news on the way again. 4G may shut down in a couple of years or less, or at least T-Mobile plans on dropping it soon.
https://www.phonearena.com/news/t-mobile-4g-lte-shutdown_id174676
Overall, there is a lot to love about Ubuntu Touch...especially the Google Pixel 3a port. However, it increasingly seems more like a form of "Pocket PC" than an actual daily driver phone capable of making and receiving calls...mainly due to things outside of the work the Linux community has been doing, such as T-Mobile's decisions.
I'd hate to waste development time on something that might not last more than a year if we get everything up and running. Also, I'm not entirely sure "new phones" without an existing Ubuntu Touch partnership would always be a permanent solution either if the hardware is not replaceable and if development happens after the release date.
Supporting a phone with upgradable software and easily upgradeable hardware (modem, etc.) might be ideal for the Linux phone community to get behind. It seems we keep hitting a long development time and a short reward time as far as phone support unfortunately.
In this sense, Ubuntu Touch's partnership with Fairphone seems like a good match if it can be expanded upon and if development can happen on a phone before release. That way it works out of the box for the longest amount of time without many issues. It will also unite the community around similar hardware.
I'm unsure of Ubuntu Touch's plans for the US. With Volla and Fairphone, it seems European users will get the most support. If Fairphone and Volla decide the US is a good market for an "Ubuntu Edition" phone, I'm sure many users would be happy. However, as if currently stands with import fees, etc. I can't say this is a viable option for most US users. For those in the US, we may have to look at alternative phone providers that will have phones supported long enough for the development time to be worth it if we are looking for a daily driver.
Again, I appreciate everyone's hard work, creativity, thoughtfulness, and experimentation. I love Ubuntu Touch and still plan on using the Google Pixel 3a. I have learned a lot during this process and hope to continue learning more. With the recent news, it just seems like to me that the opportunity window for this device to be a daily driver or main phone has already passed. Instead, based on factors outside of the Linux community, I will use this as a Pocket PC/Media Player. I have decided that it might not become a viable daily driver or "main phone."