You could use distrobox to run an arch container and access the AUR directly.

https://github.com/89luca89/distrobox

It’s what I use for some applications on Kinoite.

Take a look at the nix package manager. It is a very large and up-to-date package repo.

slackware has slackbuild iirc, arch has aur, so why not debianbuild recipes ?

Not the answer you are looking for, but you can always compile things yourself.

"Gus are you bleeping INSA--"

It's very easy to compile something after you get the hang of it. The experience varies from typing three commands (./configure, make and sudo make install) to just one. (sudo make install). And you can find out the package dependencies by reading the README file... or by just taking a look at the project directory. Or even at the Makefile file (which is a some sort of "installer" that you can edit and change to whatever you want.)

AUR like stuff is simply not for Debian. You are expected to only use software in the official repos.

• Dont Break Debian

If you want AUR you should really use Arch Linux or a easier alternative like EndeavourOS.

If you really want AUR (like thing) on Debian I recommend the nix package manager. It will do it's own thing without messing with the host OS.