Can I use ST-Link programmer for non-ST chips?
You could also flash the st-link and convert it to a Black Magic Probe.  The same image will also convert a Blue Pill into a BMP.

I've done both.  The Blue Pill has the advantage that the usb-rs232 bridge the BMP exports is easily available.

The BMP supports a range of chips to include but not limited to:
ST Microelectronics STM32F0, STM32F1, STM32F3, STM32F2, STM32F4, STM32F7, STM32L0, STM32L1, STM32L4 
Atmel SAM3N, SAM3X, SAM3S, SAM3U, SAM4S, SAM4L, SAM D20, D21
Nordic nRF51, nRF52 (These are why I use the BMP)

The BMP is open source, can be used for commercial programming and the hardware can be cheap(The "real" BMP costs around $60, a blue pill 5 pack from amazon was less than $20 shipped).