Basically if it is accepted into the mainline kernel then yes, otherwise not unless people decide to install custom kernels. Distros backport a little bit, but generally don't include anything not accepted into mainline. Then there are a few popular custom kernels that include changes not included in mainline because they are not generally useful, and only make sense for specific workloads.

Likely immediately for HEDT owners.

I make use of VFIO on my home Threadripper, and while it's "only" 12 cores and 64GB RAM, it's NUMA so I have to use thread pinning to keep cores on the same die so they're not reaching across the Infinity Fabric to the other memory controllers.

With better memory allocation, I could assign >12 vCPUs on performance oriented VMs or use more than half my memory without incurring a latency penalty.