While they generally recommend the use of the Zotfile plugin for such operations, I have had a symlink pointing my storage folder to a Dropbox folder on multiple Macs for years without issue. Just the storage folder, of course, never the data.

You can't/wouldn't use Zotero storage and a symlinked storage folder on another Cloud service at the same time. Also, you need to use Zotero storage for groups to work or the new iOS app to have your files, so this is no replacement for Zotero storage.

But yes, this would let you have your Cloud service of choice to sync attachment files between computers, while Zotero syncs only data.