It is like for the web: the minimum interop requirement is the support of noscript/basic (x)html browsers, but it is perfectly ok to run on the side a full java

It is like for the web: the minimum interop requirement is the support of noscript/basic (x)html browsers, but it is perfectly ok to run on the side a full javascript GUI which will run in the few vanguard/blackrock massive web engines (aka blink/geeko/webkit detected via the user-agent http header).