I haven't coded since I wrote COBOL on a mainframe in the1980's.

I have an account on Github, I also self host Gitea on my Start9 node, where I keep copies of Bitcoin core and mempool amongst other projects.

Do you have any specific advice for an old timer to rejoin the modern world?

Specifically, I have no idea how to pull (install) any app on Github, despite being reasonably competent Linux admin.