I really don't have the brains or energy to implement some compressed image format like PNG,

maybe you could look at QOI ("Quite OK Image format") (spec)? it's supposed to be quite simple to implement while still providing decent compression. i don't know much about it beyond this though

perhaps it is simply a much more difficult means of writing a normal computer program. one that makes the program slightly more annoying and inconvenient to run, [...]

software that is made in a deliberately odd or confusing or weird way Just Because is always fun and cool, imo