I am sort of in the same boat. I like local storage, not because of security, but because I live in an area where Internet connections are not 100% reliable. I was using Craft for that reason, but have lost interest due to their growing drive to make Craft a team application. I have long been a user of TheBrain, which uses local storage. It is available with native apps for both Windows and Mac, as well as the web. It is pricey though, but quite reliable in my experience. Another app I'm enthusiastic about is Heptabase. You create Notion-style "pages" in Heptabase that can then be stacked into whiteboards. If you're familiar with Scrintal... it's like that, but with local storage, and a nice daily notes feature. It is available for Mac and PC... and a web version is now available too.