Linux mobile phones are the fusion power of the FOSS world, always "right around the corner."
All the pieces are there, but none of them work together smoothly enough to be functional for anybody except the most hardcore FOSS enthusiasts.
When Proton started, it was kind of a joke, killed the Steam Machine idea in large part because the game compatibility was so limited. A decade later, we have a multi billion dollar handheld PC market lead by the Steam Deck, a Linux handheld that can play tens of thousands of Windows games without issue, in some cases with better performance than their native platform.
So it's certainly possible for things to completely change, but we need a big player or consortium of players to unite with a shared goal of getting a Linux Phone to the state where it's genuinely able to replace a traditional Android or Apple phone.
I'm very cautiously optimistic, I think it would come together much faster than Proton did for Linux gaming, but again, there needs to be a really heavy push into a singular device to start off. Like how the Steam Deck was, it allowed devs to have a singular platform to target for compatibility. Then, as the platform matures, competitors & innovators can enter the market and expand options, like how now there are multiple distros with builds for handhelds, like Bazzite, Nobara, and CachyOS.