yeah I should have
I got it from this switch kit on amazon, which is priced pretty reasonably for a collection of buttons
I cannot find the specific part number of the one I used but essentially any switch that is small enough and have a long stem would work, I step upon this this in particular and imo it should work
https://www.aliexpress.us/item/2251832618228674.html
also, I have a feeling that a 3d printed compliant arm can be used to allow larger switches, like this
Another method I considered is just sticking a wire in there in just the right way so that it would act as a switch when something is inserted, but that is most definitely not reliable in the long run.
I thought of about the same thing but figured that there should be enough volume in the expansion card alone to justify using larger passives. maybe those smaller component are cheaper as everyone else are using them, idk.