Smart tags for FP3+ (and compatibility with other phones or OSs)

OH has lost her keys…

She has an iPhone, so I’m thinking about making her a leather keycase for her new set of keys and sewing an Apple AirTag into it.

Then I though that I could do with an equivalent for my own keys but with a tag that works well with my FP3+. And maybe, just maybe there is an Android app that can track an Apple AirTag?

Anybody got any recommendations for such a tag and app?