Only EVT (engineering validation test) M-SoM use A5.
All DVT (design validation) and production modules use A6 and will have the version set in the hw_version field and will use A6.
You should never encounter an EVT module. It won't have a serial number sticker, so if your module has a sticker, it's definitely not an EVT.
Not having the interrupt connected to the PMIC will probably break battery detection. Battery detection works because the PMIC rapidly goes between charging and not charging, many times per second. This is why the charge LED flickers while in DFU mode. Detection of this requires the interrupt to work properly.