USB serial converters as advertised products. Ex: not counting a general purpose MCU that is known to be used for other purposes
See also: See also: max232
Ex: FT232
https://siliconpr0n.org/map/ftdi/
https://zeptobars.com/en/read/FTDI-FT232RL-real-vs-fake-supereal
https://sandboxelectronics.com/?product=ft232rl-usb-to-serial-uart-interface-chip-10pcs
Ex: CH340