Are you using the Pinephone as your daily driver?

[TRS-80]

the inability to transfer files besides an awkward workaround of pulling out a microsd card (I couldn't figure out proposed SSH or syncthing or other solutions, although they apparently work for others - I think this is solvable but I saw even a recent post where someone was struggling with it and I couldn't follow along with their solution. This was a major use case functionality failure, as I wanted to type things up and transfer them over off the Pinephone and was unable to do so - I had expected I could just plug the device in to a computer or a usb stick to transfer files back and forth);

Well if you like the click click GUI you may not like this solution, OTOH I find it cumbersome to plug a physical cable between my device and computer to transfer files when this can be accomplished over the network (and IMO that is a much more Linux-ey way of doing so).

Personally I like using TRAMP (in Emacs) but again if you prefer click click GUI you are probably not going to like that.

I think maybe software development momentum dropped off more than expected?

Maybe so. Search around Internet for posts my Martijn Braam, Drew DeVault, Tuxphones and others who have been critical of PINE64 turning into a Manjaro monoculture.

I saw someone made a backlight for the keyboard which I think is a good idea.

A backlight? Where? I've only seen where (I think it was Megi maybe) had soldered an LED to a USB-C plug and was sort of using that as a keyboard light (lol).