The "big boys" you mentioned are all holders of ARM Architectural Licenses - there are only 15 of them in total and they likely pay a shitload of money for the privilege [1].
And they will need to hold on to the ARM architecture and thus the license payments for quite the time... I bet Apple could go and develop a completely new ISA from scratch, but that would mean a third infrastructure switch in two decades on the PC and the first one on everything mobile - a lot of work for everyone involved with no real benefit, and especially after they spent multiple billions on getting their ARM stuff to the performance (in compute power and power efficiency) point they need.
Even the "biggest boys" aka nation states fail at making decent alternatives to the x86/64 and ARM duopoly - the Russian Elbrus and Indian SHAKTI CPUs are utter exotics and Chinese Loongson are a plain fork of MIPS (and again, completely exotic).
And they will need to hold on to the ARM architecture and thus the license payments for quite the time... I bet Apple could go and develop a completely new ISA from scratch, but that would mean a third infrastructure switch in two decades on the PC and the first one on everything mobile - a lot of work for everyone involved with no real benefit, and especially after they spent multiple billions on getting their ARM stuff to the performance (in compute power and power efficiency) point they need.
Even the "biggest boys" aka nation states fail at making decent alternatives to the x86/64 and ARM duopoly - the Russian Elbrus and Indian SHAKTI CPUs are utter exotics and Chinese Loongson are a plain fork of MIPS (and again, completely exotic).
[1]: https://www.anandtech.com/show/7112/the-arm-diaries-part-1-h...