Maybe he enjoys/benefits from the work, I feel like coming up with puzzle ideas would be somewhat fun/beneficial. I would definitely assume that if this were not the case he would outsource it or maybe even open source it.

I agree! There must be some sort of program written that allows them to put any image on their solar display :)

This reminds me of https://itty.bitty.site/edit, which does the exact same thing but with a size limit, no in browser editor, and if I'm not mistaken, a compression algorithm.

So with both of these cases, the site itself (github pages or bitty.site) need to be up in order to decode the content? It's not like the way images can be stored in a data URL, right?

Clarification: there is an editor you just have to create interactable hypertext files externally and drop them in