For what it's worth, you can drag a tab onto your bookmark bar, at least in Firefox.

Nifty, hadn't noticed that. I only switched back to Firefox as my daily driver a few months ago after a long time with Chrome, so I'm still finding new things.

Now we just need it to save the page state like it would for an unloaded tab. But I guess the hard parts of that aren't really implemented after all, all kinds of issues though with serializing the page state, making it work with sync across platforms, or just dealing with someone trying to open the same state multiple times...