i think i'm qualified as a chemist
as far as ozone goes, CFCs are bad, HCFCs are less bad but still bad, bromine is even worse, iodine would be worse than bromine but also it's expensive and the only compound that would be slightly useful would be CF3I which decomposes very quickly. so we can actually maybe see it used in the future, because it's basically fine
as far as GHG potential goes, the thing that is important are C-F bonds, these bonds do the IR absorption, and how fast that thing decomposes. if you introduce weak bonds decomposition is faster, a lot. C-F bonds are very strong, C-Cl a bit less but we don't want to do that. C-H are okayish, any double bond is also weak. so this is why CFCs and PFCs are very bad, because they last very long. HFCs are a maybe, not good enough so some are getting phased out now, with less fluorine these get flammable too. and HFOs degrade fast, so they're basically fine but also are expensive
the more C-F bonds and the less C-H bonds we have the less flammable thing gets, but also more stable, and by the time things get flammable it just makes more sense to switch to hydrocarbons. there are some very niche mixes that would comply with GHG requirements and are nonflammable but very few people actually need it and maybe they'll get waivers anyway