I have been tuning player pianos for many years and doing only the most minor repairs and adjustments to the player actions. I am comfortable removing and replacing the player actions to access the piano mechanism for repairs.
Late last year I acquired a 1917 Knabe upright with an Ampico player action. The player will still make some feeble effort to produce music but it needs rebuilding and appears to be all original. The piano itself is structurally sound and worth the effort to restore.
My question is would I be foolish to make this Ampico my first player rebuild or should I acquire a standard pneumatic and get experience with that system first before I try rebuilding the Ampico?

Ampicos were reproducers, which were more complicated versions of player pianos, which were pretty complicated devices themselves. I'd say no, this is not something you should do for a first-time restoration. Go for a more standardized one, like a Gulbransen or an Aeolian, that aren't as complex and much cheaper.