There is also flowsynth, GitHub - secureworks/flowsynth: a network packet capture compiler, a python tool to help create pcap files based on a configuration file.
For example, in the test suricata-verify/tests/ftp/ftp-too-long-command-first at master · OISF/suricata-verify · GitHub, you’ll see a ftp-too-long-command.syn that is used as input to flowsynth and it generates the pcap that can be found in the same directory.