Thank you again for your quick reply, and it's is good to know it's not possible right now.
While I was making Effects using PopcornFX, I felt it might be easier to see it in other viewport(side,top,persp) rather than in actual Game Viewport. (for optimization)
Somehow I was trying to connect "PK_Fx_Rendering plugin" to scene viewport camera, but I could not do it. So I ended up asking here.
Would you mind to add this as feature request?