Phones these days tend to be at least full HD (1080x1920) or more, and tablets often reach quad or higher. They are also used at point blank range (20-50cm), so the effective size and visible details are no less than on PC or TV, quite the opposite.
What many phones (even new ones) don't have is the processing power to fluidly play heavily compressed animations, because a lot of models skimp on the GPU and the CPU is too busy with rendering the video and running renpy to also decompress the files.
So, I'd recommend to be very careful with compression in the android version.