What do you mean by 'not in sheet format'? Do you want books, websites or what? Or do you, as I think cross1 seems to interpret this, as just the letter names written down, rather than dots on lines, as it were?
Just that if it's the latter, then you really ought to think again. The very essence of learning piano is reading 'proper' music, even that's just in a very rudimentary way.
Guitarists get away with it to an extent, but even then, there comes a point when ...