Not quite the same as Helium, but @Pseudozach has built an Android app that shares internet via wi-fi, it's called Lightspot.
LightSpot Mobile Wifi Hotspot Android app. Earn or Pay with Lightning. Beta version available now.

this is cool, but now comes a dumb question: how to do you pay that LN invoice if you still don't have internet access from the hotspot?
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I had the same question. The captive portal first presents the LN invoice. Then:
In my app, I allow them access for the first minute or so and they can complete payment. Obviously you need to track it so it's not abused.
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Here's a message on Telegram that starts a discussion on that: https://t.me/kriptodecom/1500
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