There are currently no Overwatch League gray skins available to collect at this time. The ones from 2018 (Tracer, Hanzo, Widowmaker, Junkrat, Genji, Mercy, D.Va, Soldier: 76, McCree, Moira) are also not available at this time for anyone who does not have them yet.
In the event this changes, I will most likely update the information here: