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I would be happy to help, if anyone with the knowledge and skills to create such a control, would be interested. I am not a developer, so it would probably mainly be testing I can do.
I just saw that this Mridula Singh released his Group Detail List control that seems to do exactly that 🙂

Customer support service by UserEcho
Hi Don Schiavone,
This looks great!
This seems exactly what I was looking for three years ago - and still is today 🙂
I will give this a spin and submit any feedback I might have.
I have also shared the link to your GitHub in this thread on idead.powerapps.com where lots of people are looking for the same.