When you get around to desktop clients, ignore the seemingly negative consensus regarding Electron[1] if you think it's the right fit for you. All the negativity I've read about it is from "purists" who aren't specifically singling out Electron; rather they are hating on all non-native implementations. I noticed the mention of Xamarin on your site; never heard of it, but I'd be weary as they seem to be oriented more towards mobile whereas you're looking for a cross-platform desktop solution which is where Electron shines.
If your goal were to be the gold standard for apps, you should be developing using native OS X APIs; the performance you get from a native implementation on OS X is astounding. However, if you do native OS X you're putting yourself in a position to do native Windows and possibly Linux apps, and the collective work required for native-everywhere obviously does not come easy or cheap - particularly if you are doing this as a solo project without assistance from a team.
Electron is a perfectly fine balance for most UIs that are fairly simplistic, which is going to be true even for the most advanced todo-type app. Extra bonus being that if you put in the effort to plan out the Electron app side-by-side with your web/browser-based app, you can share the frontend development between the two, resulting in less overall work.