Fujitsu is using custom cores, but AWS Graviton (1 and 2) actually uses Arm Neoverse cores. The Ampere Altra will too.
Re:Nvidia to Acquire Arm for $40B
by formerly_proven on Monday September 14, 2020 @10:20AM
(#24470447)
The core is not designed by ARM.
The latest Fujitsus HPC offering the A64FX is also ARM based though.[1][2] And it sounds as though this is replacing their SPARC64 in this role .
[1] https://en.wikipedia.org/wiki/Fujitsu_A64FX
[2] https://en.wikipedia.org/wiki/Fugaku_(supercomputer)