Service Discovery (ESP-NOW / BLE??) | Multiple ESP32s

[alexturner]

Hi there,

I'm building an offline IoT device that has the ability to run on it's own, but also to connect a number of units together to act as a single unit. I'm thinking the best way to achieve this is that the device will act as either a Master or a Slave.

I'd like to build a sort of zero-touch-provisioning that, when a device is selected into slave mode, a beacon message could be broadcast such that the Master detects it's presence, and can send it a configuration message to instruct the Slave to act as a Station, connecting to the Master's wifi.

Is my only choice of protocol here BLE? I could use ESP-NOW if it allowed for Broadcast messages and I had a common key across all my devices?

On the other side of the coin - if I do use BLE along side WiFi, what sort of average power consumption does BLE add?

Thanks!
Alex