You are confusing raw power and AP. For example jozu's raw power feat was lifting huge iceberg which was very impressive but his AP in named attack was not that impressive given croc endured it without much trouble.
What Jozu did was show is Lifting strength
What garp has is striking Strengthh. That's what he trained in. Punching Ships.
Adv haki equalizes raw power imo.
I see it the other way around.
Adv haki gives the same multiplicative.
Let's Just say Haki makes your attack 2x more stronger.
But Raw physical strength is something which can changed and trained.
Zoro pre time skip - 108 Pound phoenix
To
Zoro post time skip - 1080 pound phoenix
According to oda to shoot 12 pound , you need a canon of atleast a ton.
Which means. Zoro capability back then was 900kgs in pretime skip.
Post time skip it got 10x. 9000 Kgs. That's the amount of force Zoro produced in Dressrosa.
And kept training .... current is probably off the charts.
Zoro doesn't train in Striking Strength but Lifting and muscle strength. Your body should be capable of Withstanding what your releasing. Newton's third law of motion.
Just think of it as , a MMA fighter vs weightlifter.
A MMA fighter can land a stronger punch than a wightlifter , but the weightlifter won't be able to land a blow as strong as MMA fighter.
Now turn thr situation , Give each of them a sword and technique... Weightlifter will give more Explosive Results than MMA fighter.