Apptainer: Application Containers for Linux

Wish these sort of projects would do a better job articulating what the value proposition is over leading existing ones.

Like why should I put time into learning this instead of rootless podman? Aside from this secret management thing it sounds like same feature set

You should put time into learning this if you are going to be running HPC jobs on clusters, because some HPC clusters support this for jobs and not much else.

So is this popular in science or data analysis / forecasting or something like that?

I'm not familiar with it (I don't know if it changed names or just didn't notice)