Yes, except these connectors are not designed for a lot of module changes. But for 20 it would be fine. Would prefer to spend the automation time towards a production setup.
Yes, there is access to reset and also LEDs, just not the mode button. [Edit: and not USB. My initial thought is to let the first downloaded firmware set the setup flag to done, and perform a selftest and indicate the result with LED's].
Still searching I just found this indicating a timed reset, is an option:
Looking for at solution that will keep working, is this also how Particle does this?