With Bimmercode it is pretty much foolproof as long you stay out of the expert mode.
I was so scared to code my 2019 i3S Rex and just as scared to code my 2020 i3S Rex. I took the plunge yesterday. I already had a Veepeak OBD plug and I bought the $30 Bimmercode app for my iPhone. I was beyond terrified, but I coded my Rex in about 5 mins (or less).