[TheSpiceIsLife]

This is a great idea, and I'm sure many people will have use for in-browser, or in specific-app, only implementation.

I've used AutoHotKey for over a decade to do always on top switching.

   ;CTRL-SHIFT-SPACE switches the current window always on top
   ^+SPACE::  Winset, Alwaysontop, , A
   Return

I know there are programs dedicated to always on top management, but this is simple and I typically have AutoHotKey running for other reasons too, shortcuts for CAD / CAM software and graphic design.

Find AHK here: https://www.autohotkey.com/

AHK is open source, if you want to take a look at, here: https://github.com/Lexikos/AutoHotkey_L