Hi Namrog!
You can currently do a (basic) search in the search field of the Files panel that covers all text (and filenames) in your documents.
A more feature-rich search is planned, focusing on additional filtering, but I don’t have an expected release date for it.
Bonus 2: I believe many of the markdown/preview features in Deepdwn are available in VSCode, either by default or with plugins. I don’t have any plans to port Deepdwn features anywhere presently, though.