How to see which sites use my installed plugins (wordpress multisite)

You can list the sites a plugin has been activated on in the shell using WP CLI:

sites=$(wp site list --field=url)
for url in $sites; do
    if wp plugin is-active "YOURPLUGINNAME" --url="${url}" --network; then
        echo "${url}"
    fi
done

It will print out the URL of each site on its own line that has that plugin activated.