This is not a direct answer to your question, but on the topic of Zettelkasten + DEVONthink, if you haven’t already found the following thread, it might be a good one to read through for more discussions and ideas:
More generally, a lot of people have been exploring this idea. Searching for Zettelkasten or Zettel in this discourse site should bring more results, and Googling more widely will find blogs by people who discussed this too.
(I’m not posting this reply in a dismissive way; your question certainly has merit. These pointers are meant to be helpful.)