That’s what the specs say:
GPS: L1/L2/L5
BDS:B1/B2/B3
GLONASS:G1/G2/G3
Galileo:El/E5a/E5b/E6
It was this post that raised my attention for the AG-30
The AG-30 Looks like a clone of a Trimble AG-25 (still sold at $1700 or so). Of course I know that cloning a case design does not say much about the interior.