Is there a third party Tile app?

If you are looking for a tracking device then why not consider a battery powered unit that takes a sim? They are not much longer or wider than a sim, and about 1cm high.
Think of something that a HUKD version of James Bond would use.
Then you could just send it an sms and it will ping back its coordinates. PAYG or 1p Mobile sim would do the job

I didn't think you had to pay to use Tile?