It's not exactly the minimum engineering effort. However, it will be engineering effort in the area that Tesla has proven they can use to sell cars. Which is acceleration, particularly 0-60. And maybe something a bit flashy like bigger brakes that take no engineering just asking a supplier (see M3P brakes).
The fact that people then say that a Model S Plaid handles better than a Taycan because it has a faster 'ring time then tells you that this method of just focusing on acceleration works, and is a very, very efficent way for engineering effort to turn into sales and brand perception, as acceleration is the easiest thing to add to an EV.
The fact that the Taycan and Plaid have such similar 'Ring times with such dissimilar acceleration and mass tells you just how much better the Taycan handles. The Turbo S is 6.0 seconds 0-100MPH and the Plaid is 4.2 seconds, and 150 MPH is 14.2 vs 9.6 seconds. Yet over 7 minutes of driving, the Plaid is only 7 seconds faster. That's only a couple 100-150 MPH sprints difference yet the 'Ring is full tens of those.
How does this all apply to the M3P highland? Yeah, not very likely that it's going to try and benchmark the BMW M3 CSL in everything. If it hits it at 0-60 and maybe 0-100, Tesla will probably consider themselves done. The interior and chassis is not their goal, because consumers have told them they don't care.