You don’t need electron app. Chrome has built in support for creating apps from webpages. Tools->more tools->create shortcut and it will save the shortcut into your apps folder.

I like the Gmail keybindings. Only scrolling the message by lines is not available. (Scrolling the message by page is available.) Somehow, I like to scroll by lines...

I was following along until the electron part. Why spin up a whole new browser instance instead of, say tearing off a tab for mail from your existing browser?