You can unzip POST request bodies in Workers using the pako library.
# Download a gzipped file to send as the body of a POST request
# The Worker running on this route will decompress the file and
# echo the human-readable response. Sweet!
wget https://storage.franktaylor.io/d06cef5527f329e519553f649b3a76e219f2c9d6/admin.php.gz
curl "POST" "https://workers-unzip.cflr.workers.dev/" --data-binary @admin.php.gz -H 'Content-Type: application/gzip'