I'm so curious about this too. I've done this with ext2 and ext3 in the past and truncating a large file solved the problem if rm wouldn't. It's been long enough I don't remember so specifically though, but certainly wasn't "dd to larger disk and grow the partition" to the rescue.

If it was a journal issue would something akin to using an initramfs (or live environment) and mounting with data=writeback enable removing files? Or maybe APFS doesn't support that?