Probably not for a variety of reasons. The SSD itself does not know about files or appends; only block reads and writes. If the OS fills the unused space with z

Probably not for a variety of reasons. The SSD itself does not know about files or appends; only block reads and writes. If the OS fills the unused space with zeros then it's going to write a block with trailing zeros, not ones. Most SSDs also scramble or encrypt data before writing to flash.