I want to pin my most frequently used folders as favorites to the toolbar of File Explorer (just like we have a favorites bar on Edge browser).

Why is this not possible.

I use the Quick access list for that, and have Explorer set to open in it by default. I also take care that the folders all start with different letter, so I can blindly type Win+E Letter Return to open any one of the folders.

You can also add shortcuts to folders in the taskbar and use Win+Digit to open them.