How can I start learning to build a PSP-like operating system?

Start by learning how computers work at a low level: programming in C, memory models, CPU instructions, interrupts, and basic hardware communication. A first kernel project could simply boot, print text, and respond to a few commands. Later, you can add memory management, keyboard or controller input, filesystems, and graphics. A small development board can be useful for experimenting with hardware, but an emulator or virtual machine is often easier and safer at the beginning.

If your main interest is handheld games rather than operating systems specifically, try writing an emulator first. You’ll learn about CPU instructions, memory mapping, input, graphics, and timing, and you can eventually run simple programs on something you created yourself. It’s a more focused project and can be very motivating.

You probably don’t need to create everything from scratch for the final project. Many specialized devices use an existing kernel such as Linux and customize the interface, drivers, and game-focused features. Learn Python or C through small projects first, then explore Linux customization and OS development once you understand the fundamentals. Use tutorials and coding tools for explanations, but write the important parts yourself so you actually build the skills.

Building a small educational OS is difficult but absolutely realistic. Building something comparable to a modern commercial system is a completely different scale. Begin with simple programming projects, then study operating-system tutorials or a structured computer-science course. A minimal text-based OS that boots, accepts commands, and has a basic filesystem is already a substantial achievement.