You can get an 8-bit MCU if you want to explore that aspect. Modern embedded programming is often on a similar low level, and even on 32-bit MCUs you’re still poking registers and directly accessing memory with no protection. You want to display something on a screen, you can just get yourself a TFT display, write the driver yourself and send a good old fashioned byte array via SPI or parallel. Meanwhile just sending pixels to the screen on a modern PC is not at all straightforward, unless you use a library abstracting everything from you.
I recommend a 32-bit MCU like the Atmel AVR32 instead of 8 bit. The 32-bit ones aren't conceptually any more complicated. In fact, 8-bits adds a lot of complexity in doing arithmetic and updating registers with multiple single-byte writes.
Typical AVR32s give you 32 bits, 33 MHz RISC for $12. That would have been a decent workstation in 1990.
8 bit microcontrollers have the advantage that most of them are 5V devices vs 3.3V on the 32 bit ones and can also sink and source more current on their pins allowing you more flexibility to hook them up directly to USB Power or LEDs or motor drivers without conversion and from my experience are less sensitive to being bricked or inconsistent behavior from non ideal voltages applied to their pins.
