Is there any overlap between these unusual and rare words and GRE vocabulary?

The GRE vocabulary is actually based on French, Latin and Greek, not English. Much less rare and unusual once you realise that.

This is 100% incorrect as you’ve written it. The GRE is based on English vocabulary. It’s true that many words have Greek, Latin, or French roots but they are most certainly not Latin, Greek, or French.

He doesn't say the GRE is based on Latin etc. He says the GRE vocabulary is based on Latin etc. To me that sounds similar to what you're saying.