Individual applications vary of course, but I can tell you the broad rules. For high temp applications up to 350 deg F, polyester is your easy product. Most polyesters have 0 shrinkage and have a service temp rated for up to 300 deg. You will also have to use a polyester laminate, or underprint and add an acrylic adhesive. Alternatively, you will find the best durability for these applications are to screen print and clearcoat - that way you don't have to deal with the laminate as an added durability component.
Over 350, you're getting into nameplates. Chemically etched nameplates come in various metals, colors, and with options. I can't do those in house, and they're very pricey.
For things like BBQ grills, if you wanted to make them as a printer I'd print on stainless steel and clearcoat. The stainless doesn't conduct heat well and the ink should be fine up to 400-500 which is hotter than what the plate will get. The "real" way to do it would be to chemically etch.
Exhausts ... well those get over 1000 deg. The only option is chemical etching, and I'm not sure what the max service temp is on those lol. You'd have to talk to someone that makes those products.
But long story short, if a customer is looking for a cheap easy "sticker" for their very high temp application ... that doesn't really exist because it's an industrial product. If you want to sell it I would just push them to the polyester and tell them it's good up to 350 ... the rest is on them!