for line in "${asn_list[@]}";do
    res_json=$(curl -fsSL "https://stat.ripe.net/data/announced-prefixes/data.json?resource=AS${line}")
    if [ ! -z "${res_json}" ];then
        # convert json into iptables rules.v4 lines
        echo "${res_json}" | jq -r '.data.prefixes[].prefix' | grep -v ':' | sort -g | sed "s/^/-A INPUT -s /;s/$/ -m comment --comment \"drop AS${line}\" -j DROP/"
    else
        echo "Error: Unable to retrieve json for ${line}"
    fi
done

hopefully this is useful to someone, the sed expression could be modified to output other blocklist formats if needed, and rules.v6 output could be easily added as well