That's basically what a PWA is. You can "install" the app onto your phones home screen so you dont have to manage tabs. That already exists today with app.mutinywallet.com
Discussion
Yeah, heard about that, but it too often didn't work right for me, then I stopped using it for good. :D
The website has to be fully responsive, etc for this to work. Cheap websites don't do it or are only partially responsive. Sometimes, features are just straight up missing, when the website's mobile version activates. It's annoying to deal with this.