@utaylor , I do not. I just know I spent a lot of time on creating a PowerApp that integrated with Epicor (not with Epicor Functions) and got so so close but in the end I was missing some key pieces that I just could not overcome. I do not remember if this was one of them. It has been a year but this was my conclusion back then: https://www.epiusers.help/t/powerapps-and-epicor/67622/5
I remember @Mark_Wonsil telling me at a EUG meeting that he also played around with PowerApps and had some frustrations. Maybe he was able to overcome them and can offer suggestions.
I should also add that MS changed their licensing on me while i was working on it and it became way too expensive to roll it out anyway. The ROI was not there. … i still don’t think it is based on the cost of PowerApps, at least if you require a gateway to onprem.