Ok so why is m6 only a tiny increment faster.

If they made it on the same node as last time it Would basically be the same speed.

Apple are not wizards. They did the bulk of the work making m1 and the subsequent chips have just been on faster nodes

Apple is in talks to fab their new chips with Intel. You are very wrong in how their microarchitecture is developed.

Only because Intel finally has a decent node.

If they made the new m6 but with the fab tech from m1 how much faster do you think it would actually be? My guess is not much.

You can't actually do this; processors are designed for the node they are fabbed on.