MiSs_MaDmAnDy: Thank you. I'm so sorry to have offended anyone. I'll leave it here. Many thanks for all the replies
HereForTheBeer: Not sure if this is what you're looking for, but you can - apparently - add games purchased on gOg to your Steam shelf doohickey client thingamajob. I guess so it can launch right from the client or somesuch. Dunno myself since I don't use that service, but other folks have mentioned that option recently.
Obviously that doesn't do bupkis if gOg don't sell title XYZ, but don't let the lack of a Steam version on gOg necessarily scare you away from purchasing games here since they can be sorta slip-streamed in to Steamworks.