@borzel With my PWA manifest merged you can do further development work around it if you wish. However don't add to much extra Java script if you do so, as it can seriously affect performance and security.
Also too many abstractions can affect the ability to understand how Xen Orchestra, as well as XCP-ng works and fix any issues, by thus limiting the number of people who can understand the code and its workings in order to fix them. As read any code from libraries and frameworks used in order to understand them and avoid any vulnerabilities in the code.
Not to mention that people who wish to use it may not have Java script enabled browsers or have Java script disabled (maybe even blocked). If the software can't work at all without Java script in the browsers currently support available at the moment now, then they will boycott using the software or website.