Is Peter recommending that gentiles worship YHvH on Shabbat ?shalom b'SHEM Yah'shua HaMashiachAs his Word, our salvation, is preached on Shabbat.
NAsbU Acts 15:21 "For Moses from ancient generations has in every city
those who preach him, since he is read in the synagogues every Sabbath."
I don’t see a recommendation in that passage. I see a statement of fact about Jewish reading that takes place on the Sabbath.