This is some very impressive tech for just one week of work, and I really like how smooth it is to just scan a QR code to pair between the computer and the phone
There are definitely still some kinks to work out though, like others have mentioned the tilt controls were inverted for me (using a pixel 6a), and I also noticed a large amount of jitter in the motion controls (for example, the ball couldn't roll through the top-right gap in the wall that leads to the goal, because the platform was jittering back and forth fast enough that it couldn't roll through), as well as the issue that if you tilt the platform too fast then the ball will clip through (though I believe you're already aware of that one)
In terms of the marble gameplay itself, I think it's a really smart move to use this phone tech for a physics puzzler; moving and rotating the phone is very intuitive and feels natural, and it's very easy to make light and precise movements of the platform (tech issues notwithstanding)
One thing I will say, though, is that it feels like this game would work just as well if not better if it was entirely on the phone, and the phone was just a top-down perspective of the maze -- I want this game to make more use of the technology, either doing something with the dual screen, or connecting a bunch of phones to the same game (Jackbox-style), or making more use of the touchscreen, just something to really justify the tech (something to say "this tech is cool because you can do X thing that you couldn't do any other way")
Overall I think this project has a lot of promise. You've got the communication between the phone and the computer up and running, and this idea is just so creative and unique that I'm confident there's something brilliant you'll be able to do with it. I look forward to seeing your progress at the end of the production sprint!