I ordered a Pinephone. When it goes tits up in a few years I just may get a Librem. Both of these projects deserve your support, and I'm glad there's competition in the Linux phone space to keep everybody honest and innovating.
It's not 5x, it's less than 4x.
The $199 PinePhone is the one that should be used in comparisons
You can use these phones as desktops with connected display and keyboard. You can in principle run any desktop software (they call it “convergence”). Of course you need that power.
At this point I don't know what I'd want a Linux phone for anymore, and with that performance when would I use it? This will at best run as well as a $100 2GB pinebook since it is the same specs and that runs Linux poorly. Now I have to install custom scripts with a Bluetooth keyboard or ssh from my computer, with power savings so it'll be even slower. Linux on phone sounds like the equivalent of installing Gentoo on a desktop. After installing PostMarketOS on one phone I found out that you can root Android, ssh into Android, run a browser that can use desktop chrome extensions and be pretty happy with Android. Not sure what the killer app would be with those qualifications satisfied.