Have a look at SerenityOS, it's early days but I think it's a truly awesome project and expecting good things in future years. It's a completely new OS. The founder just hired two developers full time which is promising
The biggest hindrance will be, as ever, drivers. They are making consistent progress with USB and PCIe from what I can tell in the Discord. If they targeted a known platform like RPI4 and got all the drivers for that right it could be big.