Not sure if this is something you already found, but I found this from the service manual

Im very much a beginning hobbyist, so I cant make much from this, but I hope it puts you on the right path to an answer.

Here the link to the manual:

https://manualmachine.com/kenwood/ka3020se/2350744-service-manual/

It seems mouser and tme between them have all I need for now. Thats assuming the KAMOD BLUEPILL+ (WLUTOWANE ZŁĄCZA) they offer is compatible with the original blue pills and is of the same quality.

Thanks! Youre right, they dont have a large selection it seems. From the 4-5 items I’m interested right now only the STM32 blue pill and the stlink programmer for it are available, though not in stock, the rest dont seem to be.

I’ll check them out, thanks! I’m aware of tme.eu but I had the feeling its better to order bulk from them because of the shipping cost (I think last item I checked on them the shipping was more than the item), and also when I checked for the BNO085 they had the SMD variant, while I need the breakout board to more easily work with it for arduino while im learning.

Thanks, I’ll check them out!