The only things with a chance at succeeding in this space are putting USB-serial directly on the board + USB-C, or alternatively bluetooth classic RFCOMM profile. (The latter is a very long shot.)
Apart from that, this doesn't even touch upon the various voltage levels for logic-level serial ports, or the question of whether to Vref or not to Vref. (Or RTS/CTS.)
Apart from that, this doesn't even touch upon the various voltage levels for logic-level serial ports, or the question of whether to Vref or not to Vref. (Or RTS/CTS.)