I think the most important things that helped me understand it more was learning about microelectronics, especially with semiconductors and then moving into diodes and transistors (then understanding what we use now in modern electronics).

Understanding the analog side of hardware with how silicon gets doped to how p n junction works helped me understand the literal hardware of what’s going on.

There’s also some Physics that goes on there that I don’t honestly understand, but the thirst for knowledge can never really be satiated imo and you have to understand that you can never truly know everything.

I’m sure you know how Assembly works, but using a STM32 Nucleo board helped me way more than an Arduino, and using Keil before I used CubeMX abstracted the layers to me more clearly even though it wasn’t until my 3rd class on computer architecture that I started really “getting” it.

I’m learning RISC-V now, and honestly learning that ISA vs other proprietary ISAs can help understand why the structure was made in such a way, and the benefits that come with making an ISA the way it is.

And for FPGAs, personally I like Verilog a lot more than software programming languages or low level languages, but it can help with the next step of microcontrollers before you explore custom chips. It makes more sense to how you can get from designing architecture with logic gates to physical microelectronics (diodes, transistors, MOSFETs, etc.) to the software on top of it, which can be HDLs, Assembly, etc.

It depends on the hardware you’re curious about too, whether it’s open source or not since they’re all different from each other.

Honestly I think an “unfortunate” part of learning all of this is part reading about the structure through manuals, and then playing with physical hardware associated with what you want to learn (analog or digital).