granny gears are pretty basic, from my experience.
I had a 28t I took off a 7n spd bike in about 1990 to replace with a 24t, and stuck the 28 in a box where it sat for decades until my wife had a 9 spd bike with too high gearing. I changed her cassette to the largest I figured her rd could handle, and changed out the 30t granny with the old 28t, which had the same bolt pattern, and it shifted perfectly. The old 28 didnt have any ramps or pins, but as a granny, it worked fine.
I have also changed 30t granny gears on 9 spd bikes to flat, ordinary 26t chainrings, and even with sti shifters, they just plain work, shift fine and have no issues at all shifting wise with no fd futzing around at all.