Are replacement screens likely to be OEM material or tempered glass?

Fuergrissa72 you won’t find an answer to your question on this forum. We can speculate and guess but will not know for sure. We do not know what vendors do and how they procure their parts. As for the iFixit replacement screen, I suggest that you contact them directly https://help.ifixit.com/collection/130-c... to at least find out what they are doing.

I am certain that like all the other parts iFixit sells, the replacement screen offered here is made to the same specifications as the original. iFixit parts are made to specification and tested individually for quality assurance. They offer a six-month warranty and outstanding customer service.