I can speak to the BC/YC resorts. Both have a 'Marketplace' where you can buy merchandise, snacks/drinks, and order food - either order in person or mobile order. Both are slightly different and we've found them to have some very good options - you can look at the menus yourself online or in the app. We've never walked to S/D for counter service. I'm not as familiar with BW.
There is no room service. And it's pretty easy to do an instacart order to BCV, we've done it many times. I'm pretty sure you'll use the BC address since that's where they'll drop off the groceries. Remember, if you order alcohol, you'll need to pick it up in person. If you don't have alcohol, bell services will hold the order for you - if anything requires refrigeration, make sure the store separates those items and marks them for cold storage. Bell will deliver groceries to your room but will charge $6 for the service.