Consensus for this is "there isn't a one-stop tool for this in Debian, but a Debian derivative called MX offers something nearly comparable ("create an iso from current system") and Guix (maybe Nix) provide it structurally.
Beyond that it can be done manually via cfdisk/dd/rsync twiddling, or a more general "base install plus manual apt inventory", but strongly worded advice was that manually copying over config files outside the apt/dpkg guardrails is A Very Bad Idea And Don't Do That.
An question I never found an answer to, when I last asked it in I think 2019: I’m already in a Linux, of whatever flavor, is there a way for me plug a new, bare hard drive in and say “turn this new drive into a bootable install that’s just about identical to the machine I'm currently using?"
I don't necessarily mean "identical" - clone meaning "working, identical boot process, same .debs installed" would be a solid start.