Intéressant mais faire ça tout seul dans son coin est pas forcément la meilleure des solutions, je conseille de faire plutot appel à un collectif d'ulisateurs Linux de ta région, ou de rejoindre un des nombreux chat ou forum avant de se lancer.
Pour la question du routing son : utiliser Pipewire et le driver son Jack, avec "qjackctl" ou "cadence" pour le GUI.
I heard the Debian 13 "software store" gives the user the choice between dpkg repo or flatpak for some major software (ig firefox, libreoffice) and that it was pretty lightweight and efficient.
Personaly as a software developer I always use the shell and mostly CLIs and TUIs, and I use Arch/Artix btw. Sometimes I try Flatpaks (for gaming purposes) but I'm always struggling with updates and huge need in storage. For a newbie advice, on Arch, I'd say : use AppImages for the software that isn't available on Arch repositories, it's by far the easiest thing to maintain during time and is surely the lightest.
In term of distribution, for a full GUI experience I'd go for Debian, or Mint Debian edition, but sadly for some hardware you still need workarounds that need the terminal use in after the OS install / updates.