ARM licenses cores for both CPU and GPU, not just the architecture.
There are not “plenty of ARM chips designed by multiple companies”, almost all of them except for Apple (and now Qualcomm) use ARMs off the shelf design.
> Annapurna Labs, Ampere Computing, NVIDIA, Intel, Marvell, Pensando Systems, and others use Arm Neoverse and Arm technologies to create cloud-optimized CPUs and DPUs.
> Companies that have designed cores that implement an ARM architecture include Apple, AppliedMicro (now: Ampere Computing), Broadcom, Cavium (now: Marvell), Digital Equipment Corporation, Intel, Nvidia, Qualcomm, Samsung Electronics, Fujitsu, and NUVIA Inc. (acquired by Qualcomm in 2021).
The first list is basically what I said: they use licensed core designs and don’t make their own.
The second list is out of date. Intel has completely pulled out of ARM earlier this year and most of the others do not actually design their own ARM cores anymore. It’s become a lot less common in the ARMv8+ era.
There are plenty of ARM chips designed by multiple companies and built by multiple foundries