For email sync you don't need to do magic only add your google email address but you already know that. I have not tried to sync calendars or contacts, maybe that is possible. Or maybe it was just google changed something on their side and it isn't so straight forward anymore. As on Nexus 5 we do not have android support I have a feeling that syncing with google is not as easy as on Android. But maybe I am wrong. If this is stopping you to use the Nexus 5 with Sailfish OS as daily driver, you can purchase an officially supported device with Android support or just live without the constant syncing on your Nexus. I personally don't have problem with only syncing the emails in every hour or so and if I need, add a new contact or calendar entry manually. This is a fair price for getting a little privacy and not having a phone that is constantly beeping and flashing because of a 'very important' notification.