As above, it looks very much like asbestos cement board, which isn't a massively high risk. You're also right, asbestos cement board was used as an external rain screen or roof covering, whist raw fibrous asbestos was mainly used as pipe insulation, often around steam pipes.
Our lungs are pretty good at cleaning stuff that we breathe in, out, especially when we are young, so the risk of fibres remaining lodged after a one-off, short duration exposure will be extremely low.