I've gone back to embedded development as a hobby recently. A good starting point is a Arduino board. These are mostly AVR or ARM board with a set of input/outp

I've gone back to embedded development as a hobby recently. A good starting point is a Arduino board. These are mostly AVR or ARM board with a set of input/output components you can easily plug in. There is a sketch coding environment which is basically C++ with some some helper libraries. However you should be able to convert to a fully open source environment. I recently got things compiling using avr-gcc and avrdude to downloads. I'm doing all the editing in vscode. Next step for me will be bringing up FreeRTOS. You can get some dev board and components in bulk through Amazon quickly. Also many manufacturers sell their dev board directly.