That Milwaukee 2883-20 is an 18 volt (Milwaukee brand battery) cordless grinder, requiring their charger, and I firmly believe in having a 2nd battery (also theirs). I have several 18 volt Ryobi (One-Plus series) devices, and a grinder isn't one of them.
Because of the huge cost savings in not duplicating batteries and chargers, most quality cordless devices now use interchangeable batteries and chargers. You should be very sure that Milwaukee is the brand you want to keep on buying when adding to your series of devices. (You will add.)
My set started with a 1/2" hammer drill, a charger, and 2 batteries. Now it includes a sawzall, a 3/8" VSR drill, a 3/8" impact driver, a 5 1/2" circular saw, a worklight, another charger, and 2 more batteries. Be very sure you want to pay the costs for the Milwaukee brand series.
Here's the only grinder I use, and I'm currently on my 3rd one of them. Destroyed the 1st one's bearings myself, basically burned up the 2nd one as also kind of my fault, 3rd is doing great..................
4.3 Amp 4-1/2 in. Slide Switch Angle Grinder (harborfreight.com)