MTE is not the only blocker here. Pixel 7 series do not have it and are currently supported by GrapheneOS. There are other concerns regarding things like a proper secure element implementation and timely firmware/binary blob updates.

Right, but still my CarbonOS idea ('degraded' GrapheneOS) is better than /e/, Lineage, Calyx, and stock. By 'degraded' I mean the minimal changes to current GrapheneOS needed to get it working on a given GrapheneOS-unsupported device.