While I don’t have any knowledge about about app development or direct answers for your questions, it occurs to me that perhaps a piece of appropriately colored see-through acetate or maybe some stage lighting gel filter material applied to your device’s screen (like a screen protector) could be a helpful option to consider.

https://www.amazon.com/Lystaii-Corre...dp/B08NG8PLS3/

Also a quick google search for: stage lighting gels suppliers UK
Seemed to offer many options.
Maybe there’s a local place you could visit.

)BOB