Who's fought Silverado/ Sierra brake problems? and won?

Yes Chevy truck brakes are real spongy.
You can push them to the floor with vehicle off by going real slow...
Without equipment, you can still do a abs bleed.
Find a gravel road and get up to about 35 mph or faster and slam on the brakes to a complete stop.
You will hear your abs pump working.
Do this at least 2 times and you will feel increased pedal height.
You could manual bleed followed by abs bleed mentioned above.