Yes I am aware of those projects - you then need to write the software to emulate the printer itself, which interprets the control codes. We felt it was better

Yes I am aware of those projects - you then need to write the software to emulate the printer itself, which interprets the control codes. We felt it was better to have a HAT which sat on a Raspberry Pi (or other SBC), so we can offer an all in one solution which is portable, rather than sending the data to another PC via USB.