I would not hold out hopes for Android. They officially said it’s not on their Roadmap and you know what that means.
We haven’t yet gotten what’s on their Roadmap! 
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Price of iPad ain’t that bad, the cheapest regular iPad $349 USD, buy clone pencil for $15 buck will probably better than similar priced New Samsung Tablet, I have S8Ultra (regret the purchase).
Also if Shapr3d wanted to do Android! Suggestion call up Android Porting Dev Agencies in India they will take your IOS work and port it. Than you realize market Share of Android and how many of those will need 3d CAD on it.