[Campion]

From what I can tell RC’s seem to think it’s a physical object imbued with some sort of magical power.

You can't really "tell" very much, can you? You won't find any discussion of "physical objects" imbued with magical power in the catechism. The "keys" are a symbol of dynastic authority taken straight from Isaiah 22:22, not a physical object.

[RegulatorCountry]

You talk about rules, I talk about what I see and hear via online discussion by laity.