The locksmith last week mentioned a product he sells for people who regularly lock themselves out of their house. It’s a locked box that sits in your garden, which requires only a PIN(*) to open. Inside you keep a spare key. A kind of high-tech version of hiding a key under the mat / in a flowerpot / in a fake rock in the rockery.
Personally, I don’t lock myself out. It’s only ever happened once, and that was only because a visitor snibbed a lock that wasn’t meant to be snibbed. So I said thanks, but no thanks. And though I’m unlikely to ever need it, I think a better strategy for me is leaving a spare key with nearby relatives.
I suppose the other requirement of such a product is that you can remember a PIN. Maybe the next step is one that works on fingerprint ID.
(*) It’s a PIN, not a PIN Number. I suppose one could call it a PI Number.