There are different approaches to send logs to Wazuh:
You can use a OPNsense plugin to send the logs, please follow the guide provided on the website of OPNSense
You can send the logs to the Wazuh server, it can collect logs via syslog from endpoints such as firewalls, switches, routers, and other devices that don’t support the installation of Wazuh agents. Perform the steps described on the documentation
This option will give you some advantages, like the communication between Wazuh Cloud Manager and the agent being already encrypted; you will have an agent buffer in case you lose communication with Wazuh Manager. Another aspect to consider is that you will have the raw logs on your Wazuh Agent host to analyze if you need to create rules and decoders. More information can be found in
Forward syslog events - Your environment · Wazuh documentation
Please let us know if you have any questions, doubts or problems.

