Another question. Why bundling Electron or JVM and not Delphi (or its open source brother Lazarus - https://www.lazarus-ide.org/)?

I really can't understand why use HTML technologies for the Desktop...

Learning anything else other than HTML/CSS/JavaScript is too hard.

Funny enough, for anyone able to do proper Swing/JavaFX coding, the JVM applications take less space, are better integrated into the OSes and perform better than Electron ones, but it requires skill to do so.

Support tooling for web UI development is superb. I don't know the state of the art in Java/JVM GUI, but the rapid prototyping you can achieve with live code reloading, browser DOM inspectors, etc. is unmatched in my (admittedly limited) experience with UI toolkits. QtQuick is the only other that's come close for me, and it's heavily inspired by the front-end web "toolkit".

It's probably more about the developer experience than anything else. Bundling Electron in every application is pretty bloaty.

The JVM comes with an embedded Webkit browser (via the included JavaFX). This lets you code as much as you need/want in HTML/JS/CSS, but also gives you the option of easily interacting with Java, Scala, Clojure, Groovy, Kotlin, Ceylon, Frege, etc. I think this is more powerful than Electron/Chromium.

Depends on your needs. You could argue that user interface development with electron is much more convenient, you can use for example React. Basically, if you prefer developing for the browser over developing for java, choose electron, otherwise vice versa.