Well, I want any chosen window to always be on top, even if I click other windows. I often need to refer to other notes or documents when writing emails or researching.
There is no way to do that but you can arrange the windows so as not to overlap, you can split screen, you can use full screen spaces and swipe between them, you can use cmd-tab to quickly switch back and forth between apps. Macs have many methods to facilitate window and app management.
Floating is a very simple yet powerful app which lets you picture in picture (pin/stick/float) as many videos or photos on top of all windows. YouTube, YouTube playlists, Netflix, Vimeo, Twitch.TV*, Prime Video, Bitchute, Rumble, Odysee, Dailymotion, Video files and photos are supported...