COILOVERS?

I have no direct answer for you, just a note that the G6 was part of GM's Epsilon platform and other cars shared some common parts. No idea if that applies to the suspension, but it might narrow down your search if any of the others have after-market options that you can look into and research.

General Motors Epsilon platform - Wikipedia

Saab worked with GM on tuning the Epsilon platform. I forget which Saab (9-3?) uses the chassis, but there is coilovers kits for them for sport and racing. Expensive.
Just Sayin'

Megan racing euro II for Saab 9-3 is the closest I found. Will post pics when I’m done, it does require light modification from what I’ve seen so far.

Why would you put coilovers on a V6 family car?

People, if you want a lowered, loud, turboed, fast, mean car, save your money and buy one that's suitable for those kind of modifications. Get a Supra or a 300zxTT, don't put coilovers on a family sedan. Not only will cars like that blow the doors off and outhandle any G6 while they're bone stock, put $2k into them and they will blow the doors off of basically anything.

Don't waste your money.

My 06 GTP coupe six speed is no family car 😉