@jackeric as someone says, CE marking. We make and sell firewall/routers and the process to have it all tested is expensive. But it all starts in the design and ensuring compliance with electrical and safety and EMC requirements.

That said we also sell some “components”. ESP32 boards for hobbyists, etc. They are very explicitly sold as assembled PCBs to use in your own projects/products. The ESP itself has CE for the module, but as a component we don’t CE certify the board.

IANAL