Dont forget to hit that open as window tickbox, its what does the magic

I guess another issue since Im using Opera GX is that Discord could get put to sleep by GX control (I use quite agressive ram limiting). If it does get put to sleep, I would no longer receive notifications (right?).

And if you use them often, you probably will just need to type a couple of letters in address bar.

Create desktop shortcuts that opens up an existing instance of the website if there is one.
And that gives the website its own window.

If its actually a "messenger" from the side bar or just a way of making shortcuts behave this way I really dont think I care about

Some applications (such as Discord in particular) will stop sending desktop toasters (push notifications) to you when you have multiple instances or the web based client open, which means that you will only hear the notification sound, but not see the actual message without viewing it through the website. Another issue is what I mentioned in my og post, in Discord at least you would have to navigate back to your conversation if you open up a new window or tab like that.

Chrome solves this with a little tickbox "Open as window" when creating shortcuts like so:

When you click the shortcut, it makes sure theres never more than one instance running. And since it opens up in a separate Window you can feel sure that every time you press that little button, you will get the right website up as there can never be any other websites docked to the same window.

Microsoft Edge does the exact same thing, except that they've labeled the feature as installing websites as apps - although again, they do the same thing.