Is the M8 connector from the legacy spec still valid? Thanks.
The UAVCAN v1 Spec no longer defines the physical layer at all. This responsibility is transferred over to domain-specific standards, one of which is the DS-015 UAVCAN Drone Standard. The current revision of DS-015 defines only the old UAVCAN/CAN Micro connector (based on JST GH 4-pin), but it explicitly announces the possibility of supporting the standard D-Sub and the M8 you are inquiring about in the future:
So, to answer your question: yes, it is valid, but it is not yet formally specified.
OK. Good to know. Thanks.