If you're interested in doing the tech equivalent of a party trick (except that it's less interesting to watch), go ahead and try. You'll probably just end up reinstalling almost every package on the system that differs between the base distro and the offshoot. Harmless, but also pointless, since you could just have installed Debian from the get-go and saved yourself a lot of trouble.

There are a whole bunch of Very Silly Things you can do in the Linux world that aren't worth the effort unless your income relies on the creation of niche Youtube vids. For instance, it should theoretically be possible to convert a system from Debian to Gentoo without wiping and reinstalling. I'm not going to try it.

Well, it's possible, but I don't think it's feasible... If you want another distro, it's easier if you format your pc with the distro you want

The problem with package based distros (everything non-immutable) is, that a distro is very complex.

Even if you manage to "swap out" the package repositories, you usually still have a lot of remaining stuff in the background and many things tweaked by the maintainers. It's a huge mess.

In theory, you could absolutely do that, but to be honest, why bother? You already always should have a backup of all your personal data, so why not reinstall it cleanly?

Speaking of image based distros ("immutable"), the cool thing about most is that that you can easily swap out the underlying OS with just one command.

For example, you can always rebase from Fedora Silverblue to Kinoite to Bazzite to something with Hyprland and then back to vanilla Silverblue, without any traces.

So, for example, if the guy who makes your custom image on Github stops maintaining it, you can simply switch to something else in just seconds.

Maybe this is something relevant for you :)

It may just be a pre-configured Debian in which case there will be nothing to convert or it may have several additional repositories in which case it will be easier to install the new one.

It's going to go poorly and probably break. That said, I don't enjoy these "lite distros" because as soon as you load YouTube in a browser, your system specs are cooked.