Hope this becomes big, all the best. The beginnings are extremely promising. My biggest motivation behind seeing this succeed is that this is a free software alternative to Android.
With the PC/x86 architecture, you had a pretty basic standard. Even if you had things like a PCI modem that didn't work or an unsupported Ethernet card, you could always at least get a Linux distribution to boot on any PC. There are x86 systems that aren't PCs (PS4, Wonderswan, etc.) and it was the PC/BIOS standard that really paved the way for Linux back in the 90s/2000s.
I wish Windows would unlock their bootloaders. ARM+UEFI seems like the perfect platform for easily creating alternative OSes. Microsoft barely has a mobile market. They should really open their devices to the community.
One of our goals is packaging all sorts of user interfaces, and ubports is one of them (but it depends on individual developers, if they actually want to do it, because developers are encouraged to work on what they like most): https://github.com/postmarketOS/pmbootstrap/issues/62