If you want to go a more analog route, this series of synth DIY videos by Moritz Klein is really great: https://www.youtube.com/@MoritzKlein0

Not my project, but I agree!

The good thing is that there's an overwhelming amount of learning material out there. One fellow who was a big help when I was getting started was Nerd Musician: https://www.youtube.com/channel/UCyqCwyBJ98fR-CPoyXUxY5w

Look Mum No Computer[1] is the most creative and inspirational guy in this space IMO and he goes through much of his projects in further detail on his site.

[1] https://www.youtube.com/@LOOKMUMNOCOMPUTER

One of the best detailed sites on audio DSP that I've come across:

https://www.earlevel.com/main/

Here is another cool youtube channel https://www.youtube.com/@hagiwo

you can start with Bela