Arm

• M-series: bare metal
• A-series: run OS
• STMelecttronics: https://www.digikey.co.uk/en/supplier-centers/stmicroelectronics?gclid=CjwKCAjw07qDBhBxEiwA6pPbHkuMg9QMhhCH2VTpJgRsx1VAvQ8rvgfEMGvm4S13zWTIY7dhqwg8KBoCqvUQAvD_BwE
• https://www.mediatek.com/

Rasperry Pi

• https://thepihut.com/