You can export your Amazon library at the current moment, as long as the books aren’t published (or maybe purchased?) after 2023.
I did this for a friend recently and my steps were:
Started a Windows VM (if you’re not using Windows)
Install Kindle for PC app, latest version
Log in and download every book (I didn’t know how to do this in bulk so I literally right click -> downloaded every book)
Install Calibre on the same PC (I think this is necessary so it can access the Kindle encryption keys?)
Install a plugin by navigating to Preferences -> Plugins -> Get new plugins: KFX Input plugin
Install a plugin by navigating to Preferences -> Plugins -> Load plugin from file, using DeDRM 10.0.9’s "DeDRM_tools_10.0.9.zip"
Restart Calibre
At the top of Calibre, right click “Add books” and pick "Add from folder and sub-folders"
Navigate to your documents and pick “My Kindle Content”, then select “Yes” to "All ebook files are multiple formats etc"
Wait for it all to import
Select all books, then right click “Remove books” at the top and pick "Remove files of a specific format from selected books"
Pick “MD” and click "OK"
With all books selected, click “Edit metadata” at the top
Pick “Set metadata (except cover) from the e-book files”, then click OK
Done, sort of. The DRM should all be broken, and you can convert the books to EPUB or whatever format using Calibre from this point forward, even if Amazon breaks this method in the future.