OH! TIL! Apparently

                                contiguous              fragmented
    -------------------------------------------------------------------
    PCIe 4.0 NVMe Read Speed    ~5,000 – 7,000 MB/s     ~80 – 250 MB/s
    SATA 3.0 SSD Read Speed     ~500 – 550 MB/s         ~30 – 60 MB/s

> You are giving up virtually 0% to 3% of real-world performance. In daily development, media editing, and standard system use, defragmenting your SSD will yield no human-noticeable speedup.