I think this is one of those business ideas that's fallen into the "ooh, we can do everything" elephant trap. What seems like a great opportunity is really too nebulous to pin down and market.
Your demand targets are spread thinly between people who don't even know they have agoraphobia, and just don't go out because they don't like it, and others that are sufferers who completely do get it and might occasionally treat themselves to a delivery as a treat.
On the supply side, a home delivery service is equal whether the customer has agoraphobia, is too fat to fit through their front door, if they're quadriplegic and wheelchair bound, or for people with no transport. So you're going to struggle to market this to them.
An added problem is it's not a condition anyone wants! An agoraphobe doesn't want to be part of a group that makes it easier to be agoraphobic. They either need CBT or a home supermarket delivery. Both of which are solid existing competition.
It's a bit like the business of selling alcohol to alcoholics, or gambling to gambling addicts. Businesss do it all day long, for a living, but not one distillery or bookmaker will ever list it in their mission statement.
It might stop someone being unconscious due to hypoglycemia.
Solving the problem of being in a coma is pretty useful.