https://www.polygon.com/2018/5/7/17329674/nintendo-switch-online-cloud-saves

Nintendo will bring cloud saves — the option to upload game save data to the internet — to the Nintendo Switch later this year when the company’s paid online service launches.

According to the official Nintendo Switch Online website, save data cloud backups will let Switch owners save their data for easy access. But as is typical of Nintendo, details on how cloud saves will work on Switch is still unclear. “Details about this feature will be available before the paid service launches in September,” Nintendo says on its website.