The .ghx2 file format is typically the original project file, created with the GHX2 editor program. The GAXPlay program is the only program available that can read these files. The documentation is incomplete since there are a ton of unknowns, but I'll post what I have here.
Additional documentation by barncastle, Special thanks to them! https://reshax.com/topic/1020-help-issues-decompressing-unknown-lzo-compressed-data-ghx2/
Markdown formatting taken from https://gist.github.com/loveemu/9b3063ffd9a76cb18e379324e43f3251