I suppose, yes. Its also an older FS which largely has backwards compatibility. You could ask Theodore Ts'o, the principal author of extXfs. I suppose you already read this one [1]
I'm not particularly knowledgeable about filesystems, or indeed of deep Linux matters in general, but the idea of layering ZFS and ext4 strikes me as the bad kind of 'cute' solution. If you want compression, ext4 surely isn't the place to start.
[1] https://www.petri.com/compress-files-with-compact-exe
[2] https://stackoverflow.com/questions/7928840/how-to-use-compa...