The argument for it being Scarif is weak.
A better argument could be made for the Endor moon being the remote location for the construction of both battle stations.
Put Endor below the Death Star in ANH:R.
Think about it.
Remember the criticism back in the day about how did the ewoks seem so prepared to fight the Empire’s troops so quickly?
The whole thing about how did they prepare those tree/log weapons so fast?
It was generally dismissed as “Well, it’s just a movie. Yeah, it is an obvious blooper, but so what. Let it go.”
Well, if Endor was the location for both construction projects, it would be easy to assume/see that the ewoks had/have become angry with this invasion of their home/territory over the many years.
The idea would be that the ewoks alone were planning an attack on the base long before the events in Return of the Jedi. The arriving rebels just added more numbers (troops) to their plan. The capture of the small rebel force made the ewoks finally put their plan into action.
It’s obvious that the Empire would dismiss the indigenous ewoks as nothing more than meaningless creatures that were no threat to their incursion, newly constructed base and shield generator.
In fact, back in the day when I was going to rewrite the prequels, I was going to make some changes to the OT as well. This was one of my ideas.