Arduino for STM32

@ag123: Thanks for some more insight!

The only thing firm in this moment is that I have to use chip STM32F103C8 , no matter how much better others may be :-(

I managed to install the bootloader generic_boot20_pc13.bin . On connecting dmesg said:
ullix@urkam:~$ dmesg -W
[512460.235425] usb 3-2 ...

Aaah, a missing bootloader! The disadvantage when USB is integrated on the chip, but needs code for activation (unlike in the ESP family, where USB is a separate chip).

Now, I got an ST-LINK V2 and by using the ST-tools on my Linux box and st-flash I was able to write and read some bin data to and ...

I have long experience with the ESP family, but I am newbie to STM32. I got several of STM32F103C8T6 board modules like https://www.amazon.de/dp/B07Y83Q2HP, and with each got the same problem that the USB connection failed, both on Linux and Windows11. Dmesg is reporting:

[284283.729630] usb 3-1 ...