Anything online is a nope. You are entirely showing your secret phrases to whoever has access of that cloud storage even if it was encrypted or password protected. It is not worth risking all of your assets to that kind of matter.
Better have it engraved in a steel plate so that it won't be thrown away.
If you are going to use storage medias like hard drives, make sure to keep that hard drive R/W checked as I encountered some drives claiming to be in a specific size, but it was all just faked out.