A local dev environment that works.
Doing this again, and again, and again....
...truly sucks.
After not working on a codebase for a year, or two, I usually need to set up everything again -- and often run into very stupid/pointless issues that waste an hour, and often much more, just to get to the point where I can start the actual coding process.
This is pretty much why I've stopped coding. I don't have the time to waste any more.
Tools like Devbox: https://github.com/jetpack-io/devbox are making this way easier. Devbox is powered by nix, but it hides all of the complexity and makes it easier to use.