It should be low maintenance for sure. You can get SS products to remove stains if you get them.
I have a DeLorean and I just wash it with plain water and a micro-fiber cloth, followed by drying with a chamois style cloth to avoid water spots.
Recently, I had clear drips on a quarter panel that wouldn't wipe off with water or even soap and water. I tried Acetone..no go. Then I tried Mineral Spirits. That took it off completely with no residue.
I'm guessing Brasso was a joke, but I wouldn't use this unless you want the polish the whole truck. Using it on a spot will likely polish that area and make it mismatch the rest of the panel.
I'm sure Tesla will issue a maintenance guide for the stainless steel panels. From experience, SS is pretty hardy, but there are some acid based products that you need to be careful of.