I'm not a bank loan officer or anything even remotely close, but I would think there would be a problem securing a loan on a vehicle that hasn't been delivered in the sense that the bank doesn't have their collateral very easily accessible to reposses if someone is in default on said loan. I don't see that as an option for that reason alone.
But they are not required to pay for the vehicle until its delivered. I don't recall the specifics, but I believe you can sign/pre-approve a car loan, but I believe it must then get fully executed within 60? days. Otherwise you have to reapply and rates might change.
The problem here is compounded by this Ford order fiasco where ETA's are all changing or TBD. If you knew that your truck would be delivered sometime in January, you could secure the loan now.