Isn't it rather detecting UWB or pings from NFB reader? But at least the latter should work also do detect Android phones (see also https://www.reddit.com/r/RTLSDR/comments/1jsr9jv/eavesdroppi...).

Yeah that makes more sense than wifi or Bluetooth. It's probably more of a guarantee than a hard limit on only detecting iPhones. The list of devices with UWB support show all iPhone models since the 11 (except e models) but for Android, it's mostly just the pro/plus/ultra versions of the flagships.