I picked up this a couple years ago when McDonalds did a campaign for Grimace's birthday.
While the cartridge itself is not legitimately from McDonalds, the game is - they hired a company called Krool Toys to develop a brand new Nintendo GameBoy Color game in 2023, and distributed the Rom for free. As someone who had a GameBoy as their first every colors, and latter got a GameBoy color, seeing a big brand embrace a very nostalgic console was cool.
They did a good job, too - the game looks great & plays great. It's simple and sweet (see the video below), but absolutely awesome to see a retro console get some love.
When I saw that some Etsy sellers were flashing the rom onto purple cartridges, I had to grab one, shown above. While the original Etsy seller is gone now (at least, I can't find them - maybe changed name), I love that this exists.
Below is a play through of the game: