Can extractor hood be wired into oven terminal block?
To meet the electrical code in the U.S. (and most anywhere) all mains electrical connections must be done in an appropriate junction box that has been tested and listed for the purpose. As a rule, the terminal block and enclosure of an oven will have been tested for making connections to the oven cord. And it may be perfectly safe to add the hood cord as well since the box already meets requirements for flame retardance. For the sake of argument I'm assuming there is sufficient volume for the heat associated with the additional connection but that may not be the case. We don't need to figure this out because . . .

If controlling a hood is not a feature of the new oven then the terminal block box almost certainly wasn't tested for this application and therefore the connection would not meet your local electrical code.

The safe and correct thing to do is to wire the hood directly using an approved method (into a new or existing outlet or junction box). This may require changing or modifying the cord. If you are not comfortable doing this sort of electrical work then it makes sense to hire an electrician to do it. They would likely bill you the minimum for a house call plus materials.