A small team of systems programmers for months, or a dedicated teenager a week. More seriously it highly depends on how they decided to implement it, if it's a custom instruction set extension it could be relatively easy
It is a separate ML/AI accelerator with a VLIW architecture.
https://www.amd.com/en/technologies/xdna.html
XDNA is documented by AMD, but I have not read the documents, so I do not know how much work would be to make a compiler and other tools for it.
There's also a small tutorial by AMD on how to use the WMMA intrinsics[1] using their hipcc[2] compiler. Documentation is sparse kinda sparse, but the instruction set is not huge. The RDNA3 ISA guide[3] might also be helpful (and only a fraction of the pages are relevant.)
So it doesn't seem like RE is necessary? AMD dumped most code on GitHub.
0. https://github.com/tinygrad/tinygrad/blob/master/extra/gemm/...
1. https://gpuopen.com/learn/wmma_on_rdna3/
2. https://github.com/ROCm/HIPCC
3. https://www.amd.com/content/dam/amd/en/documents/radeon-tech...
[1] My bet would be that it's mostly (90%+) hard IP blocks since most of the functionality for deep neural nets is well known and the FPGA logic just glues everything together and gives them some wiggle room as architectures evolve.