How about going for an independent cloud storage like Dropbox, they are not affiliated to any OS or Windows platforms
Dropbox has had a number of security concerns[1].
Dropbox is headquartered in the US and is subject to US law, and interpretations thereof.
Dropbox has a history of taking on US government bureaucrats for roles in the company, including members of the US Intelligence Community[2].
If any of these clash with your threat model, look elsewhere? Syncthing[3] might be your thing.
1. https://en.wikipedia.org/wiki/Dropbox#Privacy_and_security_c...
2. No link, because someone "sterilized" Dropbox's Wikipedia article of those particular controversies.
Dropbox is based in San Francisco - and also needs some kind of operating system to be accessed.