Importing and screen capping software can also have the certificate software on and sign it with the metadata of the original file they’re copying, taking a picture of the screen with a separate device or pixel by pixel recreations could in theory get around it, but in practice, people will see at best a camera image being presented as a photoshopped or paintmade image, and at worst, some loser pointing their phone at their laptop to try and pass off something dishonestly. Pixel by pixel recreations, again, software can be given the metadata stamp, and if sites refuse to accept non stamped content, going pixel by pixel on unvetted software will just leave you with a neat png file for your trouble, and doing it manually, yeah if someone’s going through and hand placing squares just to slip a single deep fake picture through, that person’s a state actor and that’s a whole other can of worms.

ETA: you can also sign the pixel art creation as pixel art based on it being a creation of squares, so that would tip people off in the signature notes of a post.