If you want to provide the source to your software, you put the code on the Internet and you're done.

You don't need to even choose a licence. That only comes in to play if you concern yourself with downstream users that care about licensing.

It really only becomes complicated when you want to release it and _also_ monetise it or restrict its use.

Licenses exist because of how this is ultimately at odds with how software actually works - it's basically legal DRM.

(I think licensing has valid uses in the current environment, but it's worth keeping in mind how absurd it is as a concept, it's basically a massive hack).