The other side asks
The candidate’s questions are part of the interview.
In conversation
A selection conversation helps both sides understand the possible working relationship. Leave time for the candidate to ask about the role.
Answer the substance rather than interpreting every question as a signal about motivation. People need practical context to make a professional decision.
If an answer is not available, identify who can clarify it. A useful conversation can acknowledge an open question without pretending that everything is settled.