Hi, a time ago I found a bootable disk image witch contained a lot of tools/app to restore/recovery/backup mac osx by accident... Now I'm looking for it but I can't found (because I don't remember what it's called! Damned memory.
No idea what something like this could be called, but you could always make something. Just install MacOS to a USB drive and install any recovery programs you want to it like DiskWarrior etc.
Could this be what you were thinking of? It is a tool from Apple that makes a copy of your recovery partition onto a USB key and you can boot to it to troubleshoot. I have not used it in a while so I don't know if it even works any more with newer macOS versions.