Members with 4 wheel disc systems: Can you lock your wheels?

Just a random example from my own world............the 4WD converted 01 Dodge RAM Cummins.

https://www.forabodiesonly.com/mopar/threads/the-dummy-and-the-diesel-the-grey-whale.524619/
The 2WD truck has factory front disc/ rear drum and hydroboost. Pedal was near rock hard and LOTS of power. I once got caught in one of the damned "too short" amber traffic lights on a 55mph highway, towing the trailer and a pickup on board. I nailed the brakes and locked them up on the rear wheel ABS I was PISSED

Now that the truck is converted to 4WD, and completed in the early snow of Thanksgiving, I may not have got the air all out, OR it may be that the thing now has about 4 more feet of brake hose in the system---the "new" 4WD truck pedal is a little bit spongy but it still stops like nobody's business.

ON THE OTHER HAND my stupid "nice" low miles 04 GMC has VERY spongy brakes. 4W disk, vacuum booster with a factory vacuum pump ----- and even though decent brakes for when it's empty, I WOULD NOT want to load that truck up to near gross weight with those brakes. I have replaced the rear brakes (disk) and new front pads, bypassed the 4W ABS module, and bled them TWICE. All told I've run nearly a gallon of fluid through the thing. It is minutely better--BUT STILL SPONGY