010101 you can always test mobile/responsive mode by finding the option in your browser 🙂 this is as close to a mobile device (other than Android emulation) as you're going to get without the physical device itself.
This next image will give you a sense of the Admin UI and where the locations of the widgets would be on the forum via mobile/smaller viewport:
You should also keep in mind that the widgets you see out there in the wild Extensions tag now depend on this package as a core requirement. Though, this does not apply to the olden ways prior to this fantastic widget framework 🙂 best way to find out if it's a widget for this framework would be to look out for it in the extension OP here, Packagist in the "requires" section, or from the composer.json file in the extension's public repo.
Hope this helps!
