I recently purchased Fanatec's button cap/decal pack and I have to say, it's a very worthwhile, inexpensive, and idiot-proof bit of kit. The customization options are incredibly vast, with ~20,000 possible combinations
Fanatec GT3 Button Removal - YouTube
Button Caps and Sticker Set | Steering Wheel Accessories | Accessories | Fanatec
New: Customisable Button Caps! — Fanatec Forum
Fanatec ClupSport Magnetic Button Module + Button Caps on the Formula V2 : r/simracing