Anything of importance has deb package/official deb repo (Chrome, Brave, VS Code, Slack, Signal, Dropbox, etc), so you receive latest versions. There is flatpak as well. Newer kernel and some libraries could be found in backports repo.
I use Debian with 0 flatpaks/snaps/Appimages, only Debian repos and few official third-party ones.
I think Flatpak would be current best choice for these tasks if you are running a stable distro. But I think it would be good to have a distro where core OS and user application is completely separated, and can be updated independently. It would be nice to have latest application without fearing the next grub/DE/kernel/driver/... update might break your current setup.
There is nuance here. Technically, this is how it currently is, since the "core OS" is the kernel, and you can absolutely update that separately from everything else.
But lots of what people tend to think of as the "OS" are just applications (in Linux, anyway), so if that's the point of view, then it gets trickier. You can still update that stuff independently, but you have to decide what parts count as "core OS" to you and you'll need to update each of them independently.
True "user applications" are updateable independently.