Ask HN: How do you archive secrets for your side projects?

So, I've got a bunch of old side projects lying around, for which the majority have their code hosted on Github.

Generally, I get excited about new shiny things, and move on, and pretend to myself that one day I'll come back to whatever project I'm abandoning 'just for a few days' while I check out something else.

My side projects folder is now overflowing, but I can't clean it out easily because of all the pesky .env files which aren't checked into git, so will be lost.

How are you folks managing this?