A loan from the bank is very different than a service or subscription with the manufacturer to me

On that note, perhaps banks should be the middlemen between companies seeking recurring revenue and people seeking one-off purchases? Have the company charge $X, the bank turns that into $X/24 + interest - this already exists, but it's too tied into the credit system. Perhaps there's a space for innovation there, to make a product specialized for mediating between subscriptions and one-off purchases.

That's all of finance, translating from one to the other. At the consumer level, Klarna seems to offer to go from lump sum to subscription. Or just using a credit card, really.

Not accurate exactly. The bank finances the loan, the dealership gets the money right away. The dealership gets a small commission from the bank for being the sole proprietor of the financing. The warranties are the dealership though

If you look in the fine print, the warranties are often third party insurance companies. And the financing bank is often the OEM! And the dealer also has its inventory on credit, and the creditor is also often the OEM. Yes, there's a web of entities and transactions going on, but at some level that's accounting. You pay a monthly fee in exchange for use of the car. Making this deal with a whole ecosystem may or may not be better than making it directly with the OEM.