ESP32/ESP8266 external programmer two way design question
You could use ESP-Prog which is built specifically for this job. Comes with both UART and JTAG as well, so it give's you more options.
Comes with IDC cables so all you need is to add a small IDC connector to your board (similar to the ones on the ESP-PROG PCB)
It is not as cheap as those eBay FTDI clones but it still very cheap (~12$) and reliable.