Volunteered, perhaps uselessly, without experience making a P2P market (so skip if you only want experience from actual doers):

Same as always, you need market-making: you do it or get someone else to do it. i.e. place resting orders that others will do. e.g. in your case, maybe there is a demand for one specific kind of item: let me say GPUs. Then you be customer number one of your thing, you buy GPUs in one place and have people move them to the other place in their checked bags or whatever. Alternatively, you make the other side of the market that is highly heterogeneous (say, Indian sweets) and you or your family fly between the two locations yourself. It might teach you about the time preference of your clientele etc.

Anyway, it would seem that ultimately all markets need market-makers to bootstrap.