The Chaingun returns to Doom Eternal with a new look. It no longer requires a spinup time to fire at maximum speed, and it appears to use the same EMG rounds as the Pistol from Doom 2016.
Its Mobile Turret mod also returns to the fray, only it has four sets of barrels for maximum firepower. It also has a "gun shield" mod that blocks projectiles.
As with most other weapons in Doom Eternal, the Chaingun has several weapon skins available.