TVS for CAN lines protection need to be bidirectional?
CAN uses 2.5V +/- 1V positive levels on both CANH and CANL. It does not have negative voltages like RS-485/RS-232. So there is no point in using bidirectional TVS.
Most CAN transceivers are very rugged and can handle large voltage differencies, so depending on application and transceiver picked, TVS may not be necessary. The most modern ones like for example MCP2562FD can handle +/-58V and got built-in TVS.
In this case given the 0-7V option, a TVS somewhere around 9-12V might be suitable.