Also, one thing less-known than that Java applets were in the popular Web browsers at one point (when JavaScript was said to be just a glue language to invoke the Java applet), was that Sun already had a richer, Java-centric Web browser, which used Java for content-type handlers. Imagine providing content as data of some type/format, and the browser would automatically download an appropriate UI for that type, on the fly, and integrate it into UI, and it would all be secure.

(I first saw Java when it was called Oak, and Sun had great people doing major things, Java only one of them. When Java applets first hit conventional Web browsers, most people thought they were for replacing animated GIFs, thanks to a demo program. I probably wrote some of the first Java desktop application code outside of Sun, partly to demonstrate that Java was a real applications development language. Well, the language was there, and in many ways a huge improvement over the C++ that most shrinkwrap and technical desktop application developers were moving to, though the library support took a while to catch up, and performance took longer.)

Also on client devices running on my credit card, factory management client screens and couple of car infotainment systems.

And on client devices across many corporations still safe from Electron madness.

And as a whole (except for run in browser without plugin, which was never promised, AFAIR), they were all true or Java, relatively speaking, compared to what was available before.