This is something that I've personally wanted to try for a while, but have never had a server to try it on. Hopefully, you guys can use this.
Instead of using the traditional .jar file for people to download, use ElectronJS to create an actual application. Electron uses the basic fundamentals of web development to create cross-platform applications, meaning the application will run on any operating system. It is completely customisable, which means you can add tools and whatever you want to the application. It also comes built-in with Squirrel updater, so any updates to the client would be handled automatically. The .jar file would still be included in the .asar package, but would not need to be accessed by the end user. Instead, it would embed the .jar file into the application and run it as it would on a browser.
But JRE embeds don't work on browsers! Not to worry! There's a solution for that too. Since Electron uses Chromium, it's completely customisable. You can use the node-jre npm package https://www.npmjs.com/package/node-jre to embed the client into the application. Tons of applications currently use Electron as a base. I'm pretty certain OSBuddy and RuneLite both use Electron.
I really hope this suggestion comes to fruition. If you need any help, I've been making websites for around 10 years, and I'm definitely willing to help out.
Thanks!