But a quick look shows some Rugby and soccer cleats use a spike with M6 threading, so they are definitely not necessarily the same across sports, and maybe Bont or Sidi or someone is different.
Related: goddamnit I hate product pages that don’t include actual info about the product, finding the actual threading on either the spikes or the female thread in the shoe is basically never on any manufacturer website, sheesh.
Check soccer stores. That spec. set that jimmy posted looks exactly like a set of screw-in cleats for soccer shoes. Might be available at your local big box sporting goods shop.
Way more niche but also similar to track & field cleats. At least from a foggy memory of my javelin boot spikes. Running stores usually have a box somewhere.