Yeah a high credit score isn’t what that lender is looking for. They don’t make money of people who actually repay the loans, indeed they tend to loose rather a lot (cost of capital + cost of account admin).

If someone is offering you a 0% APR loan, it’s either because they’re hoping you’ll move your loans to them, and become unable to leave once the 0% period has ended. Or they’re trying to sell something else (either more of something, or the same thing at a higher price), and want use consumer debt to artificially increase market demand.

You upgrading a boat, so you can save money in the long term, is literally the opposite outcome they’re looking for here.

It’s not just the credit score - the APR offered is also chosen by the retailer.

0% financing costs the retailer 8%(ish) of the total amount, which is how the lender makes their money.

So in your case, the retailer didn’t want to lose that much of their margin.

0% intro APR offers are somewhat predatory in that they rely on a large portion of people keeping a balance after the intro period in order to be offered, or at least building a relationship with other financial products. It wouldn't surprise me that they would reject someone in the high 700s, they might have been looking more for people in the low to mid 600s.

There's also a lot of reasons one might be rejected for a credit line that have nothing to do with credit score. Some lenders have specific policies in addition to credit score, like Chase's 5/24 rule. Some are also just looking for "relationships" and won't offer you their best products unless you have a bank account with them, etc.