TP-link light bulb re-programming

I recently bought some TP-link smart light bulbs hoping to hack them to use Tasmota.
Unfortunately, when I stripped it down the processor was an RTL8710 so I guess not compatible with Tasmota. I have managed to connect to the processor via some contacts identified as 3V3, Tx, Rx, Gnd and using a serial to USB convertor board.
On power up the bulb squirts out the following

Initializing WIFI ...

WIFI initialized
WIFI Mode No Need To Change: STA -->STA
[wifi_set_mode] WIFI Mode Change: STA-->AP

Request ip over the range(1-128)

So that is encouraging, in that I can talk to the RTL8710. I'm hoping to be able to identify which I/O pin is used to do the pwm on the LEDs. Then I'm wondering if I can write some simple code to set the pwm value by writing to a node-red topic. I've done some code for ESP32-CAM boards where I can tell them to take a photo. I'm thinking something similar but to tell the RTL8710 a pwm value. Just very basic. I have added the RTL8710 to Arduino IDE but not tried to program it yet.
I'm wondering if anyone has tried this approach or if there are any ideas out there.