Unreleased chips

Prototype chips
Appeared on prototype hardware. Probably in FPGA form.

A14T/X/Z
Speculated names before the M-series was announced.

M1X
Speculated for iMac Pro and 16 inch Macbook Pro. Regular iMac came with M1. Was actually named M1 Max.

M1Z
Speculated for the Mac Pro. 32 cores or even 64 are rumored. Also rumored to be called M1 Ultra duo or M1 Extreme.

M2
For the second generation and speculated redesigns of the Macbook Air. Reports of them being manufactured surfaced in April 2021.

M3
Rumored to use 3nm and launch in 2023.