Tools such as Obsidian[1] are a good option for me, as I can use it as that -- a tool and not worry about the content being tied to any platform - open or otherwise. For your Vault protection, tools such as the Cryptomator[2] works well.
I reason that tools will come and go. Even for many open source ones, I had my experience of being unable to rebuild/recompile because of the outdated libraries, unmaintained code, etc. The world moves on, real fast. Plain text is and will still work in the future. I'm also OK, spicing it up a bit with MarkDown, which still can maintain human readability even if the reader doesn't know what Markdowns are.
I'm not against using tooling in a group/team, where the tooling plays a good role in making the experience smooth. I would also definitely love to pay for tools that helps the team improve and save time and frustrations.
Best of luck to your product, and I hope it serves the use cases of others who need it.