I'm surprised we didn't have any overwatch models on SGM. But here's a few I found on Steam Workshop
steamcommunity.com
steamcommunity.com
steamcommunity.com
steamcommunity.com
I'm sure there are many other OW models on the Steam Workshop these are just the ones I found after 2 minutes of searching.
Steam Workshop::Sombra Overwatch Playermodel Compressed
Steam Workshop::Overwatch | Symmetra | NPC + Playermodel
Steam Community :: Error
Steam Workshop::Pharah Playermodel




I'm sure there are many other OW models on the Steam Workshop these are just the ones I found after 2 minutes of searching.