Annotations in Finder who are readable for DT3 AND well synced via Dropbox, Google Drive & so

I’m not familiar with Tagspaces, but years ago I created a hack to do the opposite of what you want to do, I wanted to hide the .plist files in a folder so that they would not be indexed into DEVONthink. I saw from another post here that you use Hazel, so you may want to play with what I created, modifying it to fit your needs. Probably goes without saying, but test on copies of your data to ensure nothing blows up!

There are some other tips on indexing documents in that thread, but note that It was discussing working with DEVONthink 2 and as such, doesn’t apply to indexed documents in DEVONthink 3.