Experimental issues enabled by default

[xokdvium]

flakes and nix-command XP features seem to be enabled by default. I assume this is just a bug that needs to be fixed become stabilising to avoid sending a false message about the use of XP features and falling down the slippery slope.

[monyx-nuked]

could be found inside the code using search i hope

[Mic92]

It was never changed from the default. The Lix version introduced an interactive prompt for it. Whatever we do, given this is an often enabled feature set (over 95% according to some nix community survey some years ago), we should also provide a convenient way to enable it.