Bouzas: PipeWire, the media service transforming the Linux multimedia landscape

That's almost entirely wrong. One thing PA did right -- and PipeWire is following suit -- was to mimic the userspace APIs of almost all previously-existing sound server systems, so it could support almost all existing userspace programs. This was very difficult for OSS and ALSA -- it had to use an LD_PRELOAD wrapper you had to turn on explicitly for programs that needed it -- but for everything else it was more or less trivial. At no point in this does PA do anything one could reasonably describe as "soundcard emulation". Equally, PipeWire's PA emulation does not work by kicking up a copy of PulseAudio and giving it a virtual sound card: it merely provides a shared library that makes PipeWire appear to be PulseAudio to PA consumers using that shared library (basically all of them). The thing on the other end of the shared library is PipeWire, not PA-talking-to-an-emulated-sound-card.