I wonder if an EU court or anti-trust investigation might determine that this right should allow for continuous data transfer between accounts, rather than one-

I wonder if an EU court or anti-trust investigation might determine that this right should allow for continuous data transfer between accounts, rather than one-off transfers. In theory, anything you post on Mastodon could be automatically cross-posted on your Facebook page, so that your Facebook friends don't need a Fediverse account and you don't ever need to visit Facebook. The difficult part is that you really want to be able to see replies from your Facebook friends, and Facebook will argue that these replies are "personal data" belonging to those friends, not to you, so you can't ask for them to be exported.