If you are familiar with flashing on LG devices, you know what KDZ files are. KDZ is LG's preferred format for posting official firmware releases for its websites, meaning that every stock LG ROM will officially be in a .kdz format. This makes these firmware files a bit of a pain to flash through TWRP.
KDZZ by XDA Senior Member weakNPCdotCom is a tool that automatically builds flashable zip files from KDZ files. The tool is in alpha and active development stages, and currently supports two devices: the LG G6 on T-Mobile (H872) and the LG V30 on T-Mobile (H932); though you can add in support for unsupported devices through the instructions mentioned. KDZZ is also open source.
Installing the tool itself is as simple as extracting a zip file. The usage of the tool requires the Windows LG Firmware Extract Tool to extract system bins from DZ files, so you also need your KDZ file at hand. The tool can create zip packages for bootloader, modem, fullstock, or LAF (LG Advanced Flash). Accordingly, KDZZ automatically renames all the bin files, arranges them, builds the updater scripts, and zips it up. Give it a try by following along the forum thread.