Personally, I would choose to put the Apple logo first on aesthetic grounds.
Not because I like that logo better but because it is smaller. Since English reads left to right, if the short thing comes after the long thing, it looks lopsided.
Also, since the Google logo is larger, it is going to be more prominent no matter what, so putting the Apple logo first balances that out a bit. Seems fair to me.
My guess (hope) is a group of reasonable adults talking about this collaboration (remotely) decided that the order of logos was of far less importance than them working together.
Someone probably said — “how about this?” and scribbled something. May have even been a Googler.
https://blog.google/inside-google/company-announcements/appl...
Also, the Apple logo is first. I wonder how this was decided?