@ajb2k3 Thanks! Looking forward to additional tipps. My goal would be, to not require a core but to find a way to interact with it another way. If this is not possible, I concede :)
I'm keen to try out different things and be it just for the sake of trying it. Can't be bad to learn a thing or two along the way

Ahoi!

About me:
I'm a beginner with all thinks electronics. I've soldered some stuff, can program in a few languages and had some success with arduino and LED strip programming with the Arduino IDE

About the problem:
I came into posession of a M5Stack Module Plus (BN 2108264). Mainly, because I wanted a ready solution for a accumulator including loading-electronics.
No idea why I decided to go for that, especially without any clue what this M5 stuff is about.

Now I'm sitting here with this module and no idea what to do. How can I program this module? It says, that it contains a MEGA328. I'm also unable to get a serial connection. I have a bootleg pl2303hxa USB/UART cable, which I have successfully used on an Raspberry about 6-8 years ago. Tried putty and the m5burner to connect to device but no success. I tried both ports on the module. Why? Because there's a sticker that labels port A as UART and port B as GPIO. Underneath the sticker, the labelling is reversed.
Due to form factor of my cable, I've connected TX/RX to the respective pins on the ports and GND and VCC to the pinout-bar.

I've tried to understand what I could do from some google results and M5 videos on YT, but I'm totally lost.
So, well, now I'm here. Asking for help on what I can do, or maybe even what I can't do. Any help is appreciated.

Looking forward to your input!