You are mostly right, to be specific:
The file explorer in windows 11 has been writen with a framework called electron, electron's whole thing is that it allows you to code a website and have it act like an .exe application
It does this by launching a stripped down chromium browser (edge is also based on chromium) that only loads this one application's page
So yes the file explorer is running in a browser
I also have stuck in my mind:
Guys, gals, and other pals