I am not sure where to ask this but my son attends a Boy Scout troop in a small town. It is in a Protestant church building but not associated with the church. We just use the building. . It is the only Boy Scout troop and if you are Catholic and want to be a scout that is where you have to go. He will be getting his Eagle award and would like our Catholic priest to come and give the opening prayer of the meeting. Can a Catholic priest do that in a Protestant church. Even if it is just a scout meeting it will be in a Protestant church. It is hard for me to picture it.
Yes, he could.
Given that a priest can say Mass out on a battlefield, one would presume so. However, as a courtesy to the Protestant minister, someone might indicate that there will be a brief prayer offered by the priest.