If you want to learn how modern computers work, you should probably give up on the idea of building something yourself - since any modern architecture relies on

If you want to learn how modern computers work, you should probably give up on the idea of building something yourself - since any modern architecture relies on busses, peripherals and processor functionality that are way beyond hand soldered kits. Get a Raspberry Pi and accept that even light switches run Linux these days! More seriously, since the time of 8-bit CPUs, hardware has essentially split into deeply embedded system on chip designs (often ARM or RiscV cores) or monster multi-core 64 bit CPUs. The intervening 16 and 32 bit processors have largely been consigned to history (genuinely a shame - but that's the reason there are so few kits based on them). Ironically, it's the old Z80 and 6502 that are still being manufactured today in volume and at low cost as a convenient building block for simple "computer" devices. So, no - this sort of kit does not teach you how your M3 Mac works - but it does provide you with a system that you can completely understand and control, that you can build your own peripherals for, that you can write a complete operating system for, or games and programs, that you can have the satisfaction of building yet still has the basic architecture of any modern computer. And for the sort of task you're likely to undertake, it's surprisingly capable. Alternatively, if you want hardware with a simple programming model that abstracts the difficult stuff away, get an Arduino. That's really the choice you're making - either 'close to the metal' coding on older CPUs, or the modern approach of abstracting everything into software. Both are equally valid.