The problem is the UnityArchive header, which goes all the way until 0x5F. Assuming you've not already solved this, you can use a script like this one in quickbms
Code: Select all
# Script by Bartlomiej Duda (Ikskoks)
# UnityFS files (double header)
# Ver    Date        Author               Comment
# v0.1   31.12.2021  Bartlomiej Duda      -
goto 0x3A # skip first signature
FindLoc SIGN_OFFSET STRING "UnityFS"
get ARCH_SIZE asize
XMATH F_SIZE "ARCH_SIZE - SIGN_OFFSET"
# print "F_SIZE: %F_SIZE%, SIGN_OFFSET: %SIGN_OFFSET%"
get F_NAME basename
set F_OUT_NAME string F_NAME
string F_OUT_NAME += "_decrypted.unity3d"
log F_OUT_NAME SIGN_OFFSET F_SIZE
 
from 
https://github.com/bartlomiejduda/Tools
which removes all the text before 
UnityFS, but with it's offset changed so it deletes up to the second UnityFS.
you could also try just converting with the aforementioned offset, but this worked for me.
Due to the current event, I'm looking at pulling the models and repurposing them, but their bones are structured confusingly.
if you're looking at doing something similar, feel free to pm me your disc.