How does foreclosure or repossession work for a home? Do you get the home back and have to sell and pay the former buyer whatever you get that is over what they owed? That would be an important detail for me. And I'd definitely want a large downpayment in case they trashed the place, as well as proof they were paying property taxes (or might even try to set up some kind of escrow account for that).
My parents sold my grandpa's home (after he passed) to a neighbor. (IIRC, the neighbor bought it for a family member so they could live next-door.) The carried the loan for many years. I'm guessing it was 30, or at least 20. I don't know the details. The home was modest and in a medium COL area (or a low COL, by California standards). IDK why my parents decided to finance it, but it worked out well for them. I dont think the buyer ever missed a payment. My mom was thrilled when he made the final payment, only because he paid by depositing into a BoA account, and my mom loathed BofA and had so many headaches with them, and she was thrilled to be able to finally close that account. Her celebration about that is the only reason I know the approximate timeline of the loan and that is lasted at least a couple decades.
I also bought a home that was owner-financed, sort of. My dad inherited his mom's condo, and my newly-married husband and I bought it from him. We would have easily qualified for a loan, but dad offered to finance it. He liked the idea of our money staying in the family, so that the family got the interest, instead of a bank. We paid FMV for the house (with a slight discount since there was no realtor involved) and paid the going rate for interest. (My sister had just refinanced and dad and I agreed to just use the interest rate she got, since our situations were similar enough that it was a safe assumptions our rates would be as well.) We set up a lien on the property, formal payment terms, etc.
When we sold that and bought our next house, instead of paying off the loan, we just applied to the new house. We got a regular loan, and then the family loan was second, with a new lien against the new house. At one point, rates dropped and we decided to refinance and I asked dad if he'd rather we pay off the loan, or refinance to the lower rate with him. He chose the latter. We still have that loan today. My parents get a monthly check (which they don't need, but that's not relevant). Every year at tax time, we confirm with them that we both have the same number for our interest paid. Everything is above-board and official.