Does MAX A/B go for a fixed but high deceleration rate in the rollout or does it take all the wheels to the point of triggering the ABS,
Not sure about Airbus, but on Boeings, MAX is a fixed decel rate (although the rate is ramped up just after touchdown). According to my books, on the 747-400 for example, it's an 11fps^2 decel rate, using a maximum of 3000psi brake pressure. An initial brake pressure of 1650psi is applied (to give the pilot confidence it is working), then the pressure is ramped up at 150psi/sec for 2 seconds, followed by 450psi/second to the selected pressure (or deceleration rate pressure).
RTO is simply 3000psi on the brakes until the antiskid/torque limiter cuts in.