OpenMoko & friends are selling devices which basically only run Firefox, and sometimes make calls as well. The only people interested in that are diehard FLOSS enthusiasts, which means they have to use ancient hardware because new stuff doesn't have open drivers, which means that even if you ignore the app ecosystem they compare incredibly poorly to mainstream smartphones. No wonder they keep failing.
Interestingly, the desktop/laptop market is heading the other way. The move to cloud SaaS products means a decent number of people now only need a browser. What's keeping a lot of people on Windows is often literally one or two applications. Valve's push for Proton is the perfect example of this: the Steam Deck is providing a huge incentive to fix those last few bugs keeping a game from running on Linux, and with the way Microsoft is screwing up W11 it is now ironically the gamers who are moving to Linux.
What you are seeing in "regular computer stores" is mostly irrelevant. That market is basically dead. Corporate gets its machines directly from Dell/HP/Lenovo, PC enthusiasts mostly get custom builds, and casual people stick with smartphones and tablets. In-store PC sales is now reduced to a university student's Google Docs machine - and Microsoft is doing a pretty good job bribing the manufacturers to push Windows there.