Posting because I am curious about this too! Went to O'Reillys to get a piece of coolant hose cut, and saw they had some Full Syn. HM oil and this HM ATF. Curious, since O'Reilly's seems to be quality goods.
It was at one time manufactured by Pennzoil/SOPUS/RDS and I recall seeing VFAs that seemed to indicate it was every bit the same as the Pennzoil stuff.
I've personally had bad luck with any SOPUS gear or tranny fluids (also Maxlife ATFs) so Castrol would be my first choice.
O'Reilly's oils are manufactured by a Louisiana company called Omni using bulk base stocks and Lubrizol additives. I have zero experience or history with the manufacturer which is why I've always been hesitant to run it when there are so many other safe bets out there. If you were looking for a store brand oil you could go with Advance and Napa (blended by Valvoline) or STP/Autozone blended by Amalie.
I would skip it for the reason it's pricey compared to known things elsewhere. I was in an Autozone last week and they had a wide variety of Castrol atf's in gallon jugs for <$20, as well as MaxLife. I think Walmart has the same selection available for likely less.
That's a DexIII visc. fluid and this is like what you can find at other places: