Firewalld and modem connections

I would like to know if is possible to filter with firewalld a connection through a modem, rs232(tty)? According with the firewalld documentation, when is used with networkmanager, the interfaces can be assign to a zone and changes are propagated. Is it possible to assign a interface from modemmanager to a zone? or this has to be done from termninal?

Thanks in advance for your support. my OS is RHEL7 and 8.