Man, that’s not a service history, that’s a novel and unfortunately it’s a tragedy.
So, you are outside the period of the factory warranty, so a lemon law won’t help you. Also, legally, Ford is repairing everything, so it’s going to be hard to do anything with a lawyer besides spend money.
If this is the purchasing stealership, I’d strongly consider asking them to cut you a deal on a trade in. A legit deal, not a deal they would offer to some schlub off the street. Offer to trade it on a ’21, which you will expect to be under MSRP by a significant amount and your trade will be for a pristine condition Rap.
I don’t think Ford C/S will be of much help here. Even if they were to offer you a buy back, it’s several model years old and what you get for it won’t be as good as I suspect your stealership would offer on a trade. I may be wrong, so don’t discount this as a possibility, but don’t rely on it either.
Your post is pretty level headed, if you can negotiate this way, then you stand the best chance of righting the ship here. I know it’s a PITA, I’ve been through similar, but I’d start expressing a willingness to upgrade under the right, favorable to you conditions. The truck will have all manner of new driveline components and still under ext. warranty.