The shunt trips I've wired need 120v signal to trip
I've seen some with 24VDC and 48VDC shunt trip- you'd need to check the specs on the breaker as to what it needs.
Should be OK to feed shunt-trip from this panel. After all, it will have power TO shunt trip, and after shunt trip... you don't really need power anymore!
Also, you might want to note somewhere on the panel that it's configured to shunt trip. We had one go off once over lunch when a contractor working sprinklers in another part of the building opened a valve just outside a data center to bleed the system and a flow sensor shunt-tripped the main breaker and killed power to the data center. DOH! None of the ITs had any clue what had happened or how to recover, and were running around trying to figure out why the generator hadn't started. - NOTHING was labeled, neither the panel nor the sprinkler. It's labeled now.