Hi, Have you checked your building code? There are probably clearance guidelines for wood near the stove that may negate doing shiplap over the tile.

Some kind of paint is likely the least expensive option. Here's an old discussion with pictures from a person who painted their bathroom floor tile. It looks amazing.

https://www.houzz.com/discussions/5646637/paint-tile-or-leave-it-how-it-is#n=10

I wouldn't have thought of painting with a stencil, but it looks fabulous.

Check with your building codes. A lot of times it has to be tile with a designated distance from fireplace to the end of tile work. If you want it lighter, go buy and install lighter color tile.

As stated above, the distance to combustibles surrounding the stove is a key issue. Concerning gas appliances the building codes will always have wording similar to "install per the manufacturer's instructions", so the vendor's installation manual will be your guiding document. Also, if a noncombustible surround is required by the vendor, it surely will not be an entire wall of tile, so you will have personal options available for the majority of the wall.

Metal sheets?

NO painted surface or wood surface surrounding a gas stove or anything else which contains a fire.

Find what the building code allows and is safe. You may be able to lower the height, which would be less overwhelming.

There are heat resistant and flame retardant paints. Check your codes and furnace requirements for distance guidelines.