is there anyway to send only the art
You can not send album art from your local Picard installation directly to MusicBrainz online.
Your local Picard installation can retrieve/get album art from MusicBrainz online.
You can find instructions on āhow to add/send Cover Artā here:
https://musicbrainz.org/doc/How_to_Add_Cover_Art
If you are asking how to get just new artwork for your music, then try this one: Album Art Downloader download | SourceForge.net That handy tool grabs art from MusicBrainz and many MANY other places. And only artwork.
Probably an idea to also tick āsearch firstā on the MusicBrainz option.
If you have lots to do, then look at File\New\File Browser menuā¦
You can also use the full $unset list and disable all tags except for cover art:
Personally I would recommend leaving MBIDās at least, so you can update stuff whenever you want.