I've been using xen in production for at least 18 years, and although there is been some development, it is extremely hard to get actual documentation on how to do things with it.

There is no place documenting how to integrate the Dom0less/Hyperlaunch in a distribution or how to build infrastructure with it, at best you will find a github repo, with the last commit dated 4 years ago, with little to no information on what to do with the code.