Windows actually supports the always-on-top function. It just has no GUI means of activating it. But some programs use it, most prominently media players.

There are third-party tools which make it available globally, such as Ac'tivAid, written by the staff of German computer magazine c't. A quick English installation guide is at https://www.makeuseof.com/tag/pimp-windows-autohotkey-scripts-activaid-2/
Ac'tivAid also brings other Linux-Goodies, such as drag a window with Alt+LMB.