The problem is linking this data to you.
I agree, which is why I said to use an anonymous account to store it.
As far as cloud storage. All of these "anonymous email" services aren't really anonymous. And "anonymous cloud services" require that you dox yourself via paying a subscription usually. You would to find one that accepts BTC and mix the coins and hope it all goes well.
I could use Tor to sign up to a brand new ProtonMail account, and then upload an encrypted PSBT and save it as a draft. When I arrive at my destination, I use Tor to access the ProtonMail account, download and then decrypt the PSBT.
I haven't found any reasonable way to store stuff in the cloud and call it "safe".
Again, I completely agree, and would never advocate storing any sensitive data online in any manner. But the goal here is not "prevent all access to this data" (which is near impossible to achieve once you upload something to any cloud storage or similar), but rather "prevent this data from being linked to me", which is far more realistic.