This Typescript project provides functions to encode pixelart bitmaps into (in common pixel dimensions) into low-resolution color maps.

The encoded integers can be included relatively cheaply as hex input on a generic send transaction on many EVM-based chains.

While this doesn't cover the purposes of transferrable non-fungible tokens representing the art, it is suitable for proof-of-creation. There is also nothing stopping a developer (aside from cost considerations) from included the encoded integers in a deployed NFT contract, to ensure that the pixelart is stored entirely on-chain.