Headlights are headlights. Many cars used them, although I don't recall the hilux having sealed-beam headlights. It seems we were constantly replacing the bulbs on the hilux headlights. The hilux seems to be common in British places and Asian places. I've never seen one here.
I wonder if the lack of parts availability is because the Fiero is an American car, an old car, or a rare car. Or it could be the parts store's willingness and/or ability to cross-reference.
I can go to Advance, AutoZone, NAPA, or O'Reilly's and get some gaskets, the PCV, the ICM, some sensors, various brake parts, the bulbs, belts, the air filter, the fuel filter, and occasionally a starter, alternator or AC compressor. Of course, plugs and plug wires are no problem. I suspect that the distributor cap and rotor, as well as the pickup coil would be available. Internal engine parts....usually not. Shocks and springs, maybe, depending on the year.
I have noticed that parts availibility in the US is different in different areas.