>This is all absolutely correct.

Haha, I love to see those words! Just to clarify for the crowd since obviously it's easy for unversed folks to get confused, you referred to 'MCC', meaning "metal clad cable". But there's at least 3 varieties we encounter.

1: Old steel armored cable, frequently called BX, though that was a brand name. It has no bonding strip and therefore is not legal to use as ground. Obviously not on the market anymore

2: 'AC cable', an industry term for steel armored cable with the bonding strip making it legal for grounding use

3: 'MC cable' armored in aluminum, which would make it not legal for grounding, so it comes with a green wire for ground, unlike AC. So a 12-2 MC cable has 3 conductors, black, white and green, same as a Romex (again name brand) or NM (non-metallic) cable

>I personally put ground pigtails in boxes to outlets/switches for added protection since paint on the outer part of boxes can act as an insulator. I don’t trust the contact a device will have with the box as grounding in these cases, and for $10 I don’t see why I would.

Better electricians pigtail everything, so if there's a receptacle failure it doesn't break the continuity, especially of the neutral, to the downstream boxes. Wago type push in connectors beat the hell out of wire nuts for this, and everything.