Most features that appear to only be available in native apps can quite trivially be added using any cross-platform framework like Electron. Multiple windows is not something the is platform-restricted i.e. even web apps can do it if they try.
Have you given Notesnook a try? While it doesn't have multi window support they have it on their roadmap: https://notesnook.com/roadmap
Have you given Notesnook a try? While it doesn't have multi window support they have it on their roadmap: https://notesnook.com/roadmap