AFAIK the AMD distinction is currently that APUs (mobile or desktop) don't use chiplets.
On the whole my guess would be that we have the iPad Pro and MacBook Air using the same SoC, the MacBook Pro doing… something (it'll still need integrated graphics, but do they really sell enough to justify a new die? OTOH they do make a die specifically for the iPad Pro, and I'd guess it's lowest-selling iOS device v. highest-selling macOS device, and idk how numbers compare!), and the iMac (Pro)/Mac Pro using chiplets.
On the whole my guess would be that we have the iPad Pro and MacBook Air using the same SoC, the MacBook Pro doing… something (it'll still need integrated graphics, but do they really sell enough to justify a new die? OTOH they do make a die specifically for the iPad Pro, and I'd guess it's lowest-selling iOS device v. highest-selling macOS device, and idk how numbers compare!), and the iMac (Pro)/Mac Pro using chiplets.