The new 12" macbook is different. Unlike other macbooks, it charges over standard usb-c connector and therefore 3rd party chargers can be legit and good. If you get a good 3rd party charger/cable for that, you should be fine. However, finding a good one is not necessary easy task for people unknowing of electronics. Do your background research!
Other mac laptops are problematic, because only manufacturers that don't care about licensing can manufacture those, as apple doesn't sell licenses for magsafe(2).