What are you talking about? GNU/Linux has a much more healthy app ecosystem than any mobile OS.
I own one of these (the pinephone) and it's really very much like a laptop running alpine. All of my desktop apps just work (although I have to use fluxbox because CWM isn't nice on a touchscreen.)
GNU/Linux has thousands of apps. They do not all fit the screen, but it's much easier to fix than create new ones. Purism created libhandy library for that.
It should be noted that the libhandy features are now part of the stock gtk3+ framework, so every app following standard UI guidelines benefits from the new "responsive" look.
I’ve had phones with card expansion. Never worked seamlessly to the point where I gave up on them. Does anyone have experience with using cards on these phones? Can you for example store all images and media there as if it was the main storage without ever needing to think about it again?
They're first-generation devices, so the focus is on getting the device experience right, not on having flagship specifications. If they get the experience right, they'll likely come out with higher-spec devices in the future.
I have a Pinebook Pro and love it, but the Pinephone's camera is woefully underspec'd. Put a better camera on it and let me pre-order ffs and I'll buy one in a heart beat.
Preorders for Pinephone will open in about a week. You can preorder Librem 5 with a better camera now (but you won't get it very soon due to a large queue).
Yes, there are: https://en.wikipedia.org/wiki/Pinephone and https://en.wikipedia.org/wiki/Librem_5.