Yes. However, most BMSes aren't as accurate a shunt is when it comes to amp-hours in & out. I like both; if your BMS ever has a problem, you can switch control over to the SmartShunt to coordinate charging (assuming the battery is otherwise functional). And it's another data point on state of charge and the ins and outs of your system. It's not required however, you're correct. On the road, I like redundancy.I would think the CAN could be used on this battery though instead of a SmartShunt?
There's also two different purposes: shunt measures current and voltage. In a Victron system, it can be your source of truth. (Heck, in a non-Victron system, it can be the source of truth). The BMS's primary job is safety: monitor cell voltage, overall battery voltage. Stop bad things. As an extension, when the BMS is controlling charge/discharge, it can tell the inverter to stop charging, reduce current, etc. They serve different but complimentary roles.
My upcoming rebuild will have 2 shunts: main system and one programmed into DC monitor mode. It'll be wired immediately after the 48->12V step-down converter, so I can see in more detail what that part of the system is doing (and know where it's coming from).