>The blind spot then is CLI apps and tooling. Usually it doesn't matter too much being bound to system packages, but if it really does, I can always containerize those too. I only do it for my PHP dev environment.

Do you encounter any friction getting different containerised tools to talk together? Can you compose them in the classical unix fashion?

I put them on the same container, basically. I bundle my PHP binaries, modules, and tooling all together and then use it on container. It defeats the purpose a bit, but it keeps the system clean. No NPM packages cluttering everything, no composer packages leaking, etc. Cross container, I'm sure, is more complex.