FBA takes a huge chunk out of the sale's proceeds. It easily converts what would otherwise be high-margin items into losers. That's not really a scenario that your average person trying to sell a used phone would expect. The seller is also responsible for collecting (done by Amazon) and remitting sales tax (NOT done by Amazon, afaik) on FBA transactions.

The best option is to go local as a parent commenter already said. Ask the person to unbox and demo the item before you pay. If the product doesn't clearly work, leave without paying.

Yard sale groups on Facebook, Craigslist, and an active region-specific classifieds site if there's one in your area are good places to make such arrangements.

Don't meet at either party's home. The police station parking lot is best. Some police stations even have parking spots reserved for people who are performing transactions arranged online.

Safer for who? We are talking about scam buyers here not scam sellers.

Amazon handled my claim when I was scammed by a third party Amazon seller.