- E2EE
Anecdotal personal data point: I already pay $10/mo for an E2EE note app with a passable/mediocre UX. I would easily pay up to $15/mo for a polished experience like your app seems to have, and more if it becomes part of my professional workflow.
- Android and Linux support
For personal use, you may have no issue ignoring these market segments, but it might be a hard sell for teams. One of the great thing about an app like Notion.so is that it works everywhere and you don't need to buy your team members specialized devices just to interact with the project stack.
Otherwise I'm really curious to see how you handle the transition of an infinite 2D space created on large screens to smaller devices, whether it's collapsing the space in some way, or using bespoke navigation controls.