They screwed up the whole thing in v18... It worked before, regardless whether at the time of placing the order my customers were able to place an order, choose "pick up in store" (or something like that) in the shipping method, then they could choose if they wanted to pay by ATM transfer right away or with cash with "pay on site". 

NOW:

1. They can't order anything that is not in stock - which is STUPID, because for instance I can't have all different CAKES in stock all the time just waiting for someone to order. As before, I'd need the customer order, and when it's ready, the customer can pick it up. Now it just says "not in stock" and the customer can't proceed with the order. 
2. When I tried to work around it - created another "shipping method" with a fixed price (because by the way obviously no delivery fees), the customer can ONLY choose to pay via ATM, there is no option for them to pay cash when picking the stuff up. 

STUPID!!!!

Hi,

To do so, you need to enable 'On-site payment and picking' from the website settings. For detailed steps refer to the below blog:

https://www.cybrosys.com/blog/how-to-create-on-site-payments-and-picking-with-odoo-16

Hope it helps

@Jaideep  Thanks for this!   This would be the missing piece that I'm looking for, however, I don't see that module in my list of apps.    i've scrolled through them all.   There's no app that's titled 'On Site Payment & Picking' or anything similar in the collection of available apps.   Is it a 3rd party app?  

Navigate to Inventory > Configurations > Shipping Methods

and Publish "[On Site Pick] My Shop 1"

================

Updated: