Also (also mentioned this below), hinting that there's monetisation coming up but not specifying any details, will put potential users off.
There's so many payment models you could go for, like a monthly/yearly or lifetime license. I personally hate subscription-based services, no matter how cheap they are, I prefer to spend a bigger amount once. Other people will feel differently, but by not saying anything you're leaving this as a potential concern in a customer's mind as the price and payment model may not suit them in the future.
One thing you might consider is open the source but not legally leaving it open, so using a more restrictive license. Electron apps are never really closed-source anyway as it uses interpreted languages. Opening the source doesn't really preclude charging for it.
I wasn't saying this because I want the app for free (even though it seems to be free right now?). It was just my thoughts as a potential user. I personally have a pet peeve against electron, and what I would be looking for would be more barebones and keyboard-oriented anyway, so I won't use it either way. But I'm sure it will fit the needs of many others.
Anyway not all users/customers are the same but these are just my personal concerns when I saw this. I wasn't aware of Notable. I do wish you the best of luck though and I hope you can make it deliver a decent income!