"Also, it's never obvious how much someone contributed to their portfolio."

You guys are absolutely correct about the reference questions. I can find no fault with that.

However, there's absolutely no question that I'm the sole contributor to all my code. Most of my repos have only one contributor (Yours Troolie). A couple have been forked off.

I do link to a number that have been turned into larger projects; with multiple contributors, but there's no question that's happened.

Also, those are my old PHP repos; not the ObjC or Swift ones.

There's ten years of commit history in the repos. You could run crunchers on them to do things like develop velocity and productivity metrics.

I'm also quite aware that my case is unusual. Most folks don't have such extensive portfolios, and are much more of a "black box."