Comment by leoedin

Using a Raspberry Pi (or anything running Linux) is a completely different experience from bare metal. I wouldn't recommend it for learning fundamentals.

If you want to understand how interacting with peripherals and hardware works, an RP2040 is a good option - it has great documentation and sensible peripherals. Or STM32s have huge numbers of examples in the wild.

Ultimately the biggest difference - the thing you need to learn the most - is peripheral setup. Things like setting up the clock, setting up an I2C or SPI bus, reading and writing bytes from a UART etc. This stuff happens on every computer all the way up to a Raspberry Pi, but the bigger and more powerful the MCU the more it tends to be abstracted away by libraries and middleware.

If you want to truly learn this stuff you have to get low down, strip away all the abstractions and get very familiar with the 1000+ page user manual. Doing that on the simplest microcontroller possible is a benefit, because you're not overwhelmed by complex peripherals and too-many-settings.

I'd also recommend starting with C, rather than trying to mess around with Rust. Rust (and embassy) are great for building apps with very few runtime bugs, but debugging stuff in the Rust async world is a headache, and you've got an abstraction layer sitting between you and the chip.

It's actually really powerful to realise that a peripheral is just 10 memory addresses, and to make it work you just need to define a C struct and point it to the start address. Suddenly you're talking to the peripheral and can configure it. None of that is obvious with layers of middleware and abstractions.