Create a harness around the GLSL core code that can support either OpenGL 3.0 GLSL or OpenGL ES 3.0 GLSL, which differ in subtle ways. This code paves the way for me to backport to OpenGL ES 2.0.
Debug mode building on Android.
Decoupling the viewport size and the window size, although this high-dpi SDL code isn't implemented for android so I'll have to accomplish this goal another way.
Tweak tweak
Give the Android buttons a job to do so I can get out of the app when I need to.