Question
Must individual client certificates be imported in HiveMQ's truststore?
Answer
In production, we recommend using client and server certificates that are signed by a trusted CA or the internal CA of your company.
To create individual client certificates for IoT devices, create an intermediary from your ROOT CA and sign individual certificates with this intermediary.
Make sure that clients present the entire certificate chain on connection, this way, you only need to include your ROOT certificate in the HiveMQ truststore.
See this article.