Gnome is already a pretty mobile friendly desktop and a lot of work seems to be going into making it even more friendly on mobile. Has Purism hinted at trying to move to default Gnome on the librem5 eventually? Maybe a feature of Gnome 4 will be that it can work well on both desktop and mobile.
I think it would be the community’s and Purism’s best interest to try and upstream mobile friendliness to stock Gnome shell, but haven’t heard of an effort from Purism or weather they would even be interested in that. My guess is that would be a ton of work and is way in the backlog of tasks they want to accomplish.