That's not even a remotely satisfying solution.
Here's the expected flow: press power button, computer boots directly into front-end which is operable with a gamepad. User powers on the gamepad, chooses their profile and gets on with it.
If you micromanage an install of launchbox (or might as well just juggle steam installs at this stage), then you need a mouse and/or keyboard nearby. It's possibly easier to micromanage windows user accounts; click start logout, switch user, etc. Once you reach this place where you see the windows desktop, and a mouse/keyboard are in the room, then we have failed. This is no longer a gaming device, it's a PC, and what it *really* wants to do is boot up excel.
The PC desperately needs a user-experience that's competitive with games consoles, and god knows Steam is not up to the task; its multi-user is broken, you must find a phone, open lastpass, type long passwords, and do 2FA auth whenever we want to switch users.
If you could approach the console experience on a PC, you would win the market. I think you're close, and user profiles is the only major missing element.