Foolish. GM is off my list as well.
I guess we should have expected this since they weren't included in the announcement.
https://www.macrumors.com/2022/12/28/next-generation-carplay-features/
Doubt this is the new interface/stack. We still haven't seen the next-gen EVs Ford has been talking out.
My guess this is the last of the Sync 4/4A stack for EVs.
"which have totally different software on them"
Source on this? I don't believe that at all.
They have to all be running the same stack for the most part.