I got a used lid assembly from laptopscreen because iFixit was out of stock, but I used this guide and it was spot on.

Just for awareness though: the screen I received had a different lid position sensor on it than the original screen for this computer. The connector on both sensors was the same, but the bends in the flat cable didn't allow it to line up to the main board connector properly. It wasn't difficult to swap the position sensor from the original screen. There's one P2x1.5mm screw attaching it to the side of the hinge and it comes off. So, if you're thinking of doing this replacement, don't be too eager to dispose of that old screen.

Laptopscreen listed the lid assembly as fitting both A2485 and A2780 models, and I installed it on an A2485.

Thank you so much, this guide saved me a lot of trouble! I undertook a battery replacement on our CEO's 2019 MacBook Pro 16" (the glued-in kind of battery). After many hours of meticulously disassembling and re-assembling the whole laptop without a hitch, this tiny clip came out of the keyboard socket and the keyboard would not work without it. Thankfully the clip and socket were not damaged so I searched here for a solution. With this guide, a scope, and two of the super-fine tweezers from ifixit I was able to put it back into place with much less difficulty than I had expected.