PXT is their tech team supporting HR for Amazon. It grew a ton of the last 5+ years, but from the outside looking in it appears to be mainly empire building. The major initiatives I was aware of from my time there never seem to have been completed.
The idea was to build scalable solutions for HR to modernizing hiring, etc. and productize those. I'm not sure the external product piece ever panned out, but they were mainly focused on eliminated manual processes for HR inside of Amazon and migrating legacy systems to modern ones.