yes, it’s a whole different ballgame if you’re starting with an aprs integrated radio.
i use a kenwood th-d72a on the motorcycle and if i want to ‘do’ packet or advanced aprs messaging, i just use the usb cable to connect directly to the onboard tnc.
oth, i have several radios that are not keyed up with the digirig if i’m not trying to.
disabling flow control for the comport has always worked for me.
serial terminals included.
there are ‘gotchas’ with either keying method.
my allstar link and bpq32 nodes use cm108 fob with gpio ptt.
other software doesn’t have cm108 gpio implementation so rts/dtr is required.
i certainly haven’t had every combination possible though.
kb0wlf