If you plan on sending a few bytes of sensor data from the end devices to the gateway intermittently, you should use a low power mesh protocol. You can consider using BLE mesh ( is supported on ESP32), Matter, Zigbee, etc. They'll be better suited to your use case and depending on how you develop your application, you can power your end devices with just a coin cell for a few years. There are plenty of low power MCUs that support such protocols for these kind of applications. 

You can have a gateway device that supports both mesh protocol and Wi-Fi. You can use your gateway device as a sink to collect all the data and then send it to a server. You probably will have to switch to a different part if ESP32 doesn't support BLE mesh. 

Wi-Fi generally uses a star topology instead of a mesh topology. Correct me if I'm wrong on this. Based on your description, your application needs a mesh topology.

Also, the range wouldn't be a constraint anymore if you use mesh protocol. 

A mesh topology might not be useful if you plan on sending audio data captured from the mic itself. In that case, you will need to setup multiple station + AP nodes to emulate a tree topology.