yup, unfortunately the #1 thing hindering linux adoption is that the steam deck is just about the only vaguely mainstream thing sold with a linux distro preinstalled, and almost no one can be arsed to install another OS on a device.
Theoretically if you could click a button and automatically install a distro that would make a decent amount of people switch, but then that would effectively be turbomalware and shouldn't exist.
The only real ways i see linux becoming significantly more popular in a short timespan is either more linux-native devices being sold, or a strong culture developing around having us nerds install linux on people's devices.