Well, if one wants to understand how a switch mode controller's control works, they surely would learn more from doing that on a microcontroller, than just copying an appnote of a controller IC. Is it going to be easy? Probably not, but that depends more on the general microcontroller programming experience of the OP than anything else. In fact, if one's head starts to spin with control theory and poles and zeroes, it's possible they grok the whole idea much better in time domain as PID controller running on a periodic interrupt.
And I disagree about the claim that the MCU likely can't do it. Almost any MCU can, for example even the 8-bit ATTiny controllers have analog comparator which can be used to implement peak current control running at many hundreds of kHz, and voltage control loop is fine at lower BW (e.g. in timer interrupts) because output capacitance limits dV/dt anyway.
The crucial key piece between a poor-performance, randomly blowing up converter vs. a robust, easy to compensate, fast one is availability of current sensing (and of course, fast reaction to this signal). And this is well possible with any microcontroller with analog comparator peripheral. Many can be internally routed so that this signal terminates PWM cycle, you don't need to go into top-end microcontrollers for this.
And, if you are ready to invest $3 to the microcontroller, you can get stuff like STM32F334 which are specifically tailored into building complex and high performance power converters. GaN Buck operating at say 2MHz would be easy-peasy. Software-controlled switch mode converters are nothing special in 2010's, let alone 2020's. The primary advantage from a dedicated (mostly analog) IC is cost reduction in mass market products, but if OP wants to play around and learn, this is irrelevant.