I used this roofbag on my Model Y during a recent camping trip:
Amazon Basics Rooftop Cargo Carrier Bag
However, I used it in conjunction with a Thule Canyon XT basket and the Tesla roof rack cross bars. Everything worked perfectly together.
Personally, I would be very leary of putting any sort of load directly on the glass. I'm sure the glass could support a decent static load but as soon as you expose the glass to the combined effects of roofbag weight and acceleration/deceleration, shock loading from bumps, etc... that sounds like a guaranteed recipe to crack the glass.