>> I'm guessing this is in the category of "Productivity Apps", the closest competitors seems to be apps like Evernote
This is the part that stood out to me most. You seem unsure of your competitors and so you'll have limited understanding of your market and target customers. I'd start by validating the user's problem and then ensuring the product does that.
As a heavy Notion user, I'd also be curious how I can leverage what I've already built there.