I’m not opposed to it, but is there demand for it to be on GitHub?
There is! These sort of guides are best suited to be hosted at Github/lab because of their dynamic nature. Any recommendations and “best practice” today might easily become outdated tomorrow in this fast-moving Linux world! Plus you can have contributors too submitting corrections and updates (if you wish to merge 'em), so you’re not left alone doing all the work.
Here’s an example of one such guide I’ve used in the past that’s still being updated: