Thanks! I plan on releasing a beta on Android in the end of June or July.
There is no public repo yet for the app but in the meantime you can check out the Lodestone Pico a little gadget I make that will be used in multiple biomagnet related tools in the app.
Are you more interested in the NFC stuff or magnets?
NFC functionality will be very basic in the early releases and will be improved progressively.
The magnets features will mostly work in tandem with the lodestones. They are based on previous work so you can expect some fun stuff in the early releases too.