Notesnook is cool, I used Standard Notes before but the Notesnook UI is much better, especially on the mobile apps. I don’t know if they are profitable right now, but their business model is just their premium plan for 5 bucks/month. They might have lower expenses for staff though because IIRC they’re a small team from Pakistan, where wages are obviously lower than in Western countries. Everything is end-to-end encrypted and their apps as well as their backend infrastructure are open source.