Linux phones are dead in the water without significant support for apps. Currently they're all trying to build their own ecosystem, which will lead them nowhere. Ubuntu touch doesn't run Sailfish apps, PostmarketOS doesn't run any of the previous platform's apps. They all have different UX and interface guidelines and frameworks. No one will build quality UX apps for all these platforms. On desktop you can run Qt/GTK/etc in parallel with some cost on RAM usage and having to run multiple services to interface them somewhat but that doesn't really exist for mobile and they're more contained in terms of performance. Sailfish OS isn't even fully open source (entire UI stack is proprietary) and according to GrapheneOS it lacks any significant security features. Don't know how Librem and PureOS fare in this regard, but considering their focus on running on mostly open hardware, I'd assume they have different priorities right now. Once you add an Android compatibility layer you're basically kneecapping any future adoption, if your SDK was great or if app compatibility wasn't an issue anymore. It's not gonna happen in the next decade. It's like proclaiming that RISC V is gonna close in on ARM64 or x64 anytime soon. Pipedreams, unfortunately.