I need this for my Android phone to compensate for a burnt-in image.
I don't think Android has an easy to use global shader system, so you'll be stuck with overlay windows and the incompatibility they have with banking apps/DRM crapware that locks you out of your own screen without root access.
Banking apps generally set a flag on their apps to prevent overlays and screenshots to prevent malware from reading the screen and tricking the user.
Depending on your phone, this can have two effects: either the overlay is disabled automatically or the banking app detects the overlay and blocks access (ie to the PIN keypad).
Not all banking apps do this, but the ones I've used do.