Brooklyn grey isnt a difficult colour to match versus Sophisto grey etc.
Go to any BMW ARC near you and ask them to mix up a batch for you and clear coat.
watch about 500 youtube videos before you attempt this, and whatever you do, dont use that shit brush (from a tippex pen they give you) to apply the paint. sand the scratch flat, fill with paint wider than the scratch such that it is overfilled, it will dry down with a divot, add the clear coat on top.
Then use advancing grits to polish and blend.
Take the time to prepare, practice and it can be done.
Paint it on like youre painting a house and your car will look so bad that it will drive your OCD to another level and you will SEE it everytime you look at the car.