As much as I enjoy this, I feel for it to really shine would be a desktop version, not locked into the browser. I think a Chromium/Electron app would be fine.
I disagree with you. The way I work is based in realms of OS apps, not browser tabs. Electron is bloated, but for a 'cute' app like this I don't think it's any worse than Slack, or a Qt app. Overall, I'm less likely to use an app on a regular basis if I need to go to a website to use it.