After migrating to PipeWire you would want to fully remove PulseAudio. The problem is that certain packages, for example libcanberra-pulse, depend on pulseaudio even though they would work just as well if pipewire-pulse is installed. There are several relevant bugs to solve this issue, but meanwhile we could use equivs to generate a fake package that provides pulseaudio.
Copy the following file locally as pulseaudio-fake:
Section: misc
Priority: optional
Standards-Version: 3.9.2
Package: pulseaudio-fake
Provides: pulseaudio
Description: Fake pulseaudio package to satisfy depdendencies.
This solves depdendencies for packages like libcanberra-pulse when actually using PipeWire instead of PulseAudio.
Build a package from it using equivs and install it:
$ equivs-build ./pulseaudio-fake
$ sudo apt install ./pulseaudio-fake_1.0_all.deb
Now you can safely remove pulseaudio.