It also wouldn't be able to do drive a speaker, another key purpose of a Tile. Its actual tracking is primarily passive, so it's hard to locate with just a phone. (You might be able to triangulate from multiple phones... I recall an HN article with somebody doing that a few weeks ago). The main use case is to get close enough to trigger it, then follow your ears. That's thousands of milliwatts.

I suppose it might be possible to add a capacitor that's being continually charged.