a seatbelt sensor wasn't federally required by law until 1972?. just like back up lights were not required prior to 1967, and lighted side-marker lights prior to 1969, etc.
that said, the "head lamp on warning buzzer" is likely the most useful feature of the light package. but I do like those fender turn indicators, too. The ignition key lamp delay is slick, also. I lived out in farm territory for a while, where it's pretty dark at night. that ignition light is pretty slick.
there may be generic stuff out there, the mods required to the wiring harness may not be trivial. and with wiring harnesses 50+ years old, brittle and cracking, some may leave it be, if all is working well.
if you want to add these options, seek out the individual OEM wiring components. they come up for sale, from time to time. those are about as plug-n-play as you can get. that said, using the wiring diagram from the FSM, you can fabricate your own that plug in just as naturally.
the circuits are really, really, simple, compared to modern day electronics, so it's easy to fabricate your own with some basic skills.
there is likely NOT enough people seeking and demand for someone to make and market a specific 1970s Barracuda light package wiring options. I'm not sure that ever existed or implemented.