To me stm32 has a huge learning curve (may be because I'm on Linux). But I don't know an alternative that would be that universal. I use Chibios for firmware. I don't use CubeMX because the code and API it generates is absolutely not to my liking. It's fine for led blinking, but when I tried more sophisticated programs I found Chibios much easier to use. Still difficult nonetheless.
BTW, I'm giving esp32+8Mb psram + micropython a chance. But it doesn't have many IO pins, so I'm stuck with SPI displays.