I made a github repo of my last paper published in an Elsevier journal. This was cool because I could put the latex and simulation code for others to copy. https://github.com/lewis500/distribution-of-trip-lengths
The final version differs a little bit because they had a copy-editor go through and make some good improvements, even after the referees made their comments. Interestingly, the journal was fine with my linking to the repo within the text of the paper, as a way to share the code.
There is nothing like real open access though. This journal has wonderful typesetting and such and is totally free: https://www.jtlu.org/index.php/jtlu/article/view/835/860
It's funny what tricks they use to justify their existence. Always emailing me about bizarre author features no one will use. Makes me sad to think of the engineers sitting in a big room year-on-year polishing features no one will use.