Years ago I bought a kit for my '96 Riviera. It wasn't thin... Was a wood grained kit, but was about 1/16" thick. Laser cut so the edges were round. Looked like a very thick clear lacquer like on Rolls Royce's or such. Held up to anything and made that bland dash a lot better.
Seems I can't find them anymore, it's all this thin vinyl stuff.....
They looked great in your Riv, but these kits vary greatly in execution, granted I can't say I've seen the 89-93 kit(which no one buys because they came with it!!!) but the if the ones made for 94-97s are indicator they look like thick randomly shaped fridge magnets, clearly sitting above the clearly visible dash surface below.
The trim usually doesn't fade but the plastic surrounds do. You can disassemble those and swap the "wood" they're actually thin aluminum with wood wrap) if you bend the tabs on the back.