I have made a tool which can repack ba2 files from Fallout 4, it is still work in progress
This games has 2 different formats of BA2 files.
1 – GNRL = general format archive
2 – DX10 = texture format archive
My tool can, so far extract all formats.
Also my tool can repack files with format GNRL only, also with compression.
Still gonna work on repacker for DX10 archives..