Tilengine itself doesn't require any special hardware. You need SDL2 for the window, but that's an optional component. Going to the metal, your target hardware should provide a 32-bit RGBA framebuffer and video output bus. The Paspberry Pico doesn't have one. There are some high-end microcontrollers with framebuffer and video, but most common configuration is to use a specialized display controller with external RAM and a bus. So, if you ever manage to build an embedded system with such configuration and over 500 MHz CPU clock, you could compile and run Tilengine on it without any OS.