Traditional "slow" IrDA is essentially HDLC over UART with packed based protocol stack over that, that among other things can emulate dumb reliable duplex pipe

Traditional "slow" IrDA is essentially HDLC over UART with packed based protocol stack over that, that among other things can emulate dumb reliable duplex pipe (TCP-like) that is usually exposed as virtual serial port, bluetooth is similar, with significantly larger set of "other things". Other relation to serial port is that it is usual interface between the HCI and host system (using fairly highlevel protocol). In the lower layers it is frame based protocol that has no relation to serial ports.