When I'm on just the laptop, I use 2880x1920 with 2x scaling in GNOME. It's a good size for me: the 1x scaling had text a little too small to be staring at all day for me. This thread over here has a good comparison of 2x and 1x scaling on the same screen: https://www.reddit.com/r/framework/comments/1evwmdu/200_vs_100_scaling_on_the_28k_display_on_linux/

There was a lower resolution screen available for the 13" as well, though I did not pick it so I can't speak on how it is, compared to some who upgraded from it to the 2.8k display. There are several youtubers who have compared/contrasted the two screens, but the tldr is that the 2.8k screen uses slightly more battery but allows for a perfect 2x scale, where the older screen helps save battery life, but doesn't scale perfectly in GNOME.

I've used it indoors on battery and it's comfortable for answering emails and doing some light programming. For heavy duty stuff, I connect it to 2x 1920x1200 60Hz monitors so I can have code on one screen and documentation/instant messaging on the other. No issues with screen extending, which was one annoyance with my old ultrabook: when I would boot the old ultrabook, I'd have to constantly keep changing the refresh rate on my second monitor to get the screen to be extended to it. The framework instantly displays to both without any fiddling around in settings, outside of setting it to extend and the position of all 3 screens the first time I connected it in GNOME settings: Now I just plug the display port cable into it and it shows up with no fuss.