That was I had in mind when I asked the question. Right now, I can do a podman run -it --rm alpine busybox sh anyday of the week, but it doesn’t hook up on my home directory, nor provide any of the nice things toolbox enter provides.
It’d be super handy to be able to do a toolbox enter ubuntu and be greeted by an Ubuntu user space as if I was running it, just like toolbox enter brings me a modifiable Fedora environment.