Of course it’s an iPhone chip, which is why it’s got just 8 gigs of RAM. I think it’s the same exact SoC that went into the 16 Pro Max.
If so, it's a binned version with fewer working cores.
This suggests someone may be able to install MacOS on an iPhone with some modification.
There were some M-series chips with 8 gigs, iirc. There was a whole debate going on about that on the net when they were released. Not the M5 though, as it seems.