Aside from your preference for debian-based distros, you’re describing Garuda pretty well. But the chaotic-AUR is enabled by default, so you’d never need to hunt for .deb files in the first place. And the update script, “garuda-update”, has a bunch of nice features by default, like taking snapshots and running grub-update (which would have prevented the grub fiasco that hit the arch-based distros a while back).
The only pain points are 1.) If you don’t like Garuda’s theming, you’ll need to do some minor ricing to start, and 2.) Plasma 6 updates often enough that on a rolling release distro, something minor about your setup might break once every few months, e.g. KDE allows themes to set a minimum taskbar size and all of a sudden your taskbar increases in size, or your wallpaper gets reset for some reason.
Garuda. It’s even easier than Manjaro. The theming can be a bit much, though.