Good question… I’ll take a stab at answering.
First, we don’t consider Universal Blue (uBlue/ublue/etc) to be a distinct distribution of Linux. This is Fedora, and depending on which flavor you install, it’s Silverblue, Kinoite, Sericea, Onyx, etc… (those listed are official Fedora “Immutable”/Atomic Desktop flavors).
Second, what uBlue does different from the official releases is that we’re taking advantage of a still (officially) experimental feature ostree native containers. This feature was originally slated for Fedora 38 but now for Fedora 40. It works quite well, but for full distribution support, the Fedora team is working to cleanup rough spots, etc.
More technically, the difference is that container images can be used as the remote storage and transport mechanism, rather than the ostree specific repos which had been used. However, on the user’s system, the differences are very limited. The main difference is the different remote URL one sees.
Regarding infrastructure… Fedora has to host their bespoke ostree mirrors with partners, etc… but for ostree native containers, we can use any container registry to host the images. The uBlue project uses Github to provide Continuous Integration and build automation, plus the Github Container Registry (ghcr.io) for hosting our images. As a DIY user who wants to build things on their own, one may choose any registry, including one self-hosted at home.
Certainly we’ve put an emphasis on using “cloud-native” tooling, CI, Containers, etc to build our extension to Fedora.
Also, while any user can DIY it if they desire, and we try to keep a core set of images suitable for further customization, much energy has been put into the “ready to go” desktop Bluefin and the gaming oriented Bazzite.
For more info you can take a look at the uBlue website where some of the info above can be found, and more.