Bluetooth puzzle

[ndjurov]

I’m connecting up to 70 different sensors to an ESP32 board. These sensors will be infrequently polled from a host application running on a tablet or a smartphone. I’m using ESP-IDF framework and at the moment, I’m using WiFi, Berkeley socket APIs and Windows based tablet for this. However, in order to leave the WiFi available for other purposes, I would like to replace the WiFi with Bluetooth and the final goal is to develop a host application for Android tablet, rather than Windows based one.
I’m not familiar with Bleutooth so I read as much as I could about it, both Classic and LE, but I’m still puzzled by many issues. Would you please help me with the following:
a) I found some examples of socket APIs being used with RFCOMM. It would be very simple conversion for me. However, there is only one place in ESP-IDF documentation that briefly mentions that RFCOMM is implemented in the BTU layer, but I can’t find any instructions how to use it. Some forum members think that RFCOMM is not available at all in the newer versions of ESP-IDF.
b) I found some examples of SPP approach (ble/spp_client_demo.c) that looks like an acceptable approach. However, I don’t know if I can use it to communicate with both Windows and Android based host application.
c) Any other suggestions and directions are welcomed and appreciated.

Thanks a lot.