It's less an "app" and more a set of recommended extensions that work well together. At the end of the day you have markdown files in a directory, however you want to manage and sync them (git, dropbox, rsync, whatever).
https://foambubble.github.io/foam
My personal setup also integrates heavily with my Zotero toolkit for tracking and storing papers and other materials.
As with all things, its a matter of tradeoffs. Dendron started its life as a standalone app (eg. think Obsidian) but I quickly realized I was spending most of my time building undifferentiated editor scaffolding instead of focusing on the hierarchies and schemas that made Dendron unique.
I wanted to spend more time building out features that supported Dendron's [hiearchy first approach](https://www.kevinslin.com/notes/3dd58f62-fee5-4f93-b9f1-b0f0...) to note taking which is what led me to re-write it for VSCode.
That being said, the core dendron engine is not vscode specific and there are folks that are experimenting with porting it over to other editors (eg. sublime, vim). We also have plans for a standalone editor in the future (most likely, this will be a fork of VSCode optimized for note taking)
For notes I'm (currently) using Obsidian.md, which has many of the same benefits of the previously mentioned systems. I settled on it because it allowed me to easily import notes from the previous apps and they are stored as simple markdown files. Which means I can access them using vi if I'm on a system that doesn't have Obsidian installed.
While I enjoy VSCode, most of my development is done in Visual Studio. And occasionally vi/vim for smaller applications.
For me org-roam doesn't scratch the portability itch (easily add notes on my phone etc), but I'm actively looking for alternatives I can make the jump for, and rely on it not disappearing in a few years
I really like the idea of this extension, but as mentioned I'm not sure this existing only in VSCode helps me much at this point.
Props for releasing though, great to see this revolution in note taking apps, and shifts in thought around the optimal way to take them.