There's no linux-firmware package on Debian. I guess that's one of the major changes that makes Ubuntu different from Debian, under the hood.
Anyhow, on Debian:
- firmware-linux: Meta package, depends on:
- firmware-linux-free (that one really is a sammelsurium)
- firmware-linux-nonfree: Meta package, depends on:
- firmware-misc-nonfree (big one, could well be made into a meta package depending on vendor-specific packages)
- firmware-amd-graphics (another big one)