Maybe you could zip up like 1000 pictures and upload that to cloud storage.
And you are 100% sure that your cloud storage won't do anything at all to that file? And you are 100% sure that unzipping will create the exact same files as before? Bear in mind that even changing a singe bit anywhere renders your wallet lost and essentially impossible to recover. Too risky.
You can upload that zip to many places, copy it to a few hard drives and such.
I may be wrong on this, but I'm pretty sure that you can't alter a zip archive (other than opening it and archiving the contents again) without making it unusable. Sure, you could modify its metadata, but that won't alter the files inside of it. I'm also pretty sure it has error correction, so a password-protected zip archive stored in multiple places could work.Maybe it wasn't clear, but I myself wouldn't use it and don't recommend using such a scheme.