Forgive me if I'm missing an obvious solution, but I can't seem to crack this particular nut.!
Backstory: Our greenhouse is partnered with a delivery service which comes by on a weekly basis. Customers interested in having their plants delivered contact the delivery service directly, either before, or after they have an order with us, and then the delivery service comes once a week to pick everything up, then delivers the plants to where they need to be (we don't receive any money for said delivery).
At the moment, it works by customers choosing regular curbside pickup, and (hopefully) leaving an Order Note saying that they're going with the delivery service so we don't have to chase after them for confirmation afterwards.
I'm looking for something which would, at checkout, allow online store customers to choose this delivery service among the other options, after which an email containing the order information to be sent to said delivery service. Almost like a custom fulfillment service, but products/inventory wouldn't have to be assigned anywhere else, and would remain assigned to our regular storefront location.
Honestly, I could even do without the "send order email to the delivery service" feature - just having the delivery service be be listed as an option would do wonders.
Note: We are nowhere near large enough to go with Shopify Plus, and the delivery service is still a startup, so they're not able to fund a custom app.