The ones coming in a fewyears are a little more telling as they will also track location etc. On the older vehicles disconnecting it a few minutes generally killed their memory but not the programing. IOW on some Dodge Vans for example if you unhooked the battery it would take an hour or two driving for it to completely retrain engine timing etc in some cases.
Again you’re behind the times. Any car with a built in GPS/ navigator has it now, and those have been moving down from the luxury cars very steadily the last 10 years.
Why go through all that work? It’s completely pointless. The computer itself only stores about 5 minutes worth of data, handy in crash reconstruction. Long term storage is done with devices like Progressive uses, don’t want the data long term, don’t plug one in.