Well… Actually, monopoly is used in French for things that isn’t stricly speaking the sole actor (sorry). There are concurrence (mostly in the form of AMD and Intel in the PC DGPU market, and others in phone/mobile GPUs).

And for mobile operating system, they would count as a duopoly. Aside of IOS and Android, there isn’t much (thought Android is a bit special by the fact it can be reused by other vendors without the google-specific parts).

Actually, maybe the DGPU market could be seen as a triopoly (not much choice beside Intel, AMD and NVidia).

(and if we don’t use the term of monopoly, we can still say for sure they are the main provider of DGPU, which is very likely to cause competition issue)