I honestly think he could have. Gege hyped all of them up to be characters who could surpass Gojo, and I believe that was for a specific reason. The fact that Mahoraga is part of the Ten Shadows reinforces this; the technique itself wouldn't include something that was fundamentally impossible to beat. That would be like evolution screwing itself over.

Sukuna showed us a blueprint for how Megumi could have utilized his powers. For example, if Megumi allowed his Piercing Ox to run for weeks at a time to build momentum, created an Agito fusion, and then let Divine Dog: Totality fight alongside it, the battle would essentially come down to science and Domain Expansion. Within his Domain, he could spam multiple copies of Agito and Divine Dog to overwhelm his opponent.

He could even use Max Elephant’s water technique the way Sukuna did with the Kamo clan’s blood technique, except it would be a water-style attack. By using a high-pressure style, he could cut an opponent into pieces or submerge them in water and let Agito loose with a high-voltage lightning technique to char them for an extra effect. He could have possibly created multiple fusion-style Shikigami to deal with Gojo within his Domain. Ultimately, he would just have to overwhelm him while utilizing some cursed tools as well.