Oskar 2.8.3 does not support cuda arch 9.0 required for optimal performance on Grace Hopper GPUs, but it was fixed in 2.11.1
https://github.com/OxfordSKA/OSKAR/blob/e07c9c81c375ec45e4118f49b397009c737606ec/cmake/oskar_compiler_options.cmake#L248
I think Hoppers will still run 86, just sub-optimally