It is truly loaded. Looks to have the Limited option package with that Caddy steering wheel. https://www.ebay.com/itm/264290801271?ul_noapp=true
The single chrome is a power recliner. I don't know what the black one is but it doesn't look factory.
The black switch looks to be heated seats, which would have had to be added at some point. Definitely not a 1979 Buick option.
Wonder how much better it would do with the OE radio, Buick road wheels and whitewalls? And report on the climate control system functionality?