I'm trying to test a new appdata file for an application and I'd like to install it so it can be searched and found by GNOME Software or similar software centers. Software is using appstreamcli to perform the search?

Perhaps the command appstreamcli search?
Can anyone explain how this command finds the metadata? Where is the metadata database?

For example, how can I check where these data are fetched from:

$ appstreamcli search lilypond | grep Name
Name: GNU Denemo
Name: feta26
Name: Rosegarden