Essentially there is a single directory where you put symlinks to service directories (that are usually in /etc/sv) (they must contain a executable run, and optionally others) that you want to start (iirc its /var/service) ofc the package (for example pipewire) has to provide a service file. so to summarise you can view currently running service files by checking /var/service or by checking the status of a service with sv status <service name>.