If I want to develop SDK to support cross platform(ex:android, linux) using my codes, do I need to make wrapper layer?

After I have developed certain features based on android(using java), linux(using c++),

then If I want to make SDK(library,documents,test tool,etc) that support android and linux.

But I am confused whether I need to make wrapper layer.

case 1) Do I need to make wrapper layer to support java(for android) and c++(for linux)?

1-1) In case of this, I worried that it can cause code complexity and performance issue.

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case 2) If I don't need to make wrapper layer, client should make two application to working on android and linux. In case of this, I think my SDK can not to say to support cross platform.

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currently, I think case2) is more general way and good for performance.

how do you think about it?

I wonder how to make most SDK do.(case1? or case2?)