Yes! GET /v1/{appId}/conversations/{conversationId}/messages gives you a list of all the messages from a conversation. Which also has a field readBy, which is an array containing the user ID of every person that read the message.

If the array does not contain the user you want to fetch the read status of, then they did not read the message yet. Note that readBy will never contain the user ID of the message sender.

The messages API reference: messages object:

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