It feels like the opposite to me. Moving providers with my Linux VM is incredibly annoying, but with these things, I can (so far) literally ask them to create me a tarball with a README.md and hand it to an agent on the new provider and have it do the rest.
Possibly so for now. But do you think the providers are interested in making interoperability easy?
Even in the future if they are required by law to provide it, I wouldn't bet against the craftiness of the providers to invent some sort of network effect dark pattern to make it painful, if not outright impossible.
Just as an example, with Muse I can already see that the way they are thinking of making money is via taking a transaction cut, so it's not that hard to imagine that Meta can negotiate deals for txns that happens through Muse which won't be available elsewhere.