My lovely bride spends a fair amount of time taking care of her 97 year-old father who is still quite spry. Having said that, he has taken to hiding his house/mailbox keys “for safety reason” and sometimes it takes quite awhile to find them. We are considering the purchase of an AirTag to put on the keychain.
I’m guessing that her iPhone 7 Plus running the latest 15.x.x. can set up the AirTag, but won’t be able to run the “Precision Finding” feature. If this is correct, will the AirTag still help us to find the keys?
You are correct. An iPhone 7 doesn’t have the radio circuitry necessary to precisely locate a tag.
You can still get coarse-level information (which will, for instance, show you if it’s at home or at work or wherever).
Once you are at that location and want to locate it further, you can tell it to start beeping. You will then have to listen for the beep in order to locate it.
Needless to say, if it’s not in a location you can easily hear (e.g. in your car or several rooms away from your current location), this may not be all that easy.