Edit: This is incorrect, as pointed out below.

Pulseaudio still does the device juggling etc on most systems even when there's a pipewire backend.

Wrong. Pipewire is pulseaudio-compatible, and the device juggling is done by wireplumber

Are you sure? On every device I could quickly reach (Gentoo, NixOS, Pop OS, all with vanilla/default pipewire configs), `ps aux |grep -i pulse` only turns up pipewire-pulse.