I'd love for it to be included by default too. In the meantime, I found a guide to use Pipewire on Zorin that I pulled from r/pop_os:
# Add ppa for latest build
sudo add-apt-repository ppa:pipewire-debian/pipewire-upstream
# Update
sudo apt update
# Install components
sudo apt install gstreamer1.0-pipewire pipewire-media-session libspa-0.2-bluetooth libspa-0.2-jack pipewire pipewire-audio-client-libraries
# If you get unmet dependencies, you can run:
sudo apt --fix-broken install
# Then re-run
sudo apt install gstreamer1.0-pipewire pipewire-media-session libspa-0.2-bluetooth libspa-0.2-jack pipewire pipewire-audio-client-libraries
# Reload new services
systemctl --user daemon-reload
# Disable PulseAudio service
systemctl --user --now disable pulseaudio.service pulseaudio.socket
# If you update from previous version of PopOS
systemctl --user mask pulseaudio
# Enable Pipewire services
systemctl --user --now enable pipewire pipewire-pulse
# Enable Pipewire media session
systemctl --user --now enable pipewire-media-session.service
# Reboot and possibly use https://extensions.gnome.org/extension/906/sound-output-device-chooser/
Haven't tried this setup with Reaper yet but it's been working great so far otherwise.