but do you know setting for arc.ini does it work ?
[External compressor:7zip]
header = 0
packcmd = 7za a -txz -an -mcrc=0 -mf=off -myx=0 -mmt=4 -m0=lzma2{

ption} -si -so <stdin> <stdout>
unpackcmd = 7za x -txz -an -y -si -so <stdin> <stdout>
*what to change to brotli ??