Whatever you use.... use a real computer or otherwise to connect to "the Cloud" and backup the files to CD/DVD or USB thumb drive or hard disk
and store Offline.I have offline copies of my doc's, cave, music, etc, because cloud services go down often w/o notice/warning or could get malware on just One machine/device that looks for all devices on local networks and wipe/encrypt them.
With computer etc w/ USB3 ports and drives you can backup huge files often faster then many NAS boxes and Any "Cloud" sevices.
One I have is 1TB WD My Passport used laptop size HD but built to plug directly to USB3. (Does work w/ 2 but slow and draws less power.)
you can get USB HD and Flash w/ hardware encryption so if "disk" is lost/stolen, the data is secure. Unlike most Cloud services that will give all files to Govmnt and many others.
Many tablets/phones can use USB flash but most won't have enough power to run USB HD even when plugged into AC.
notes
most flash drives will store files for months to a few years but isn't made to be an archive for store data long term.
Data on Burn CD/DVD can last for years but can have problems to read on other players/burners. Often worse if you burn @ max write speeds.
That can be bad thing to backup important files you need to restore a few years later.
While HD hardware can die... won't just lose data in a few months or years.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave