Can we add a feature that allows searching/filtering my notes?
You can search with Ctrl + F if you are using Firefox
But I think that doesn’t exist any option yet in the app
You would need an extensive plugin because it has to search and index all your documents. Other systems do this by creating their own index file (a database) or use a third party or open source free text search.
there’s quite a lot of them - 42 here - https://www.predictiveanalyticstoday.com/top-open-source-big-data-enterprise-search-software/