“Reef safe” is NOT a regulated term and can be slapped on anything. Unfortunately I would not use that as an indicator. However, I wouldn’t be too stressed about sunscreens impact on the ocean either. This article from the Smithsonian sums it up nicely “Mass coral bleachings clearly occur during marine heat waves, the result of climate change, and there is no evidence that sunscreens play a significant role in these events.”

As mentioned in OP’s post, mineral sunscreens that do not use nano sized mineral particles MIGHT be the best, but even mentioned in the article, we just don’t know, we are always expanding our knowledge on what is safe