With the caveat of it not being a portable single file, I find custom image-based Linuxes fill this gap perfectly. There's of course Fedora Silverblue / Fedora

With the caveat of it not being a portable single file, I find custom image-based Linuxes fill this gap perfectly. There's of course Fedora Silverblue / Fedora Bootc with https://universal-blue.org/ https://universal-blue.org/ and https://blue-build.org/ https://blue-build.org/ being good examples. Recent developments have seen the creation of bootc images for non-Fedora distros too, and at this point I've seen quite a few cool arch-bootc custom images, completely customized to the author's desires. See: https://github.com/bootcrew/ https://github.com/bootcrew/, https://github.com/tartaria-dev/tartaria https://github.com/tartaria-dev/tartaria