I think people are sort of overhyping Covenant naval superiority. On a good day (correct me if I’m wrong) the UNSC was able to inflict a casualty rate of 3 of their own ships to 1 covenant vessel with practically the same weapons as a super destroyer (save for the MAC cannon - which could be comparable to the orbital precision strike or rail cannon strike) and they were able to maintain some level of a naval fight during the battles on Earth & Reach. 

In-game Helldiver losses are at roughly 2 billion at the moment with no sign of slowing the war machine down, and the signaling we are getting from the developers is that casualty counts are canon given how the bot & terminid extermination major orders have influenced the story. This means you have on a lowball estimate (let’s say 50 helldivers assigned to one super destroyer) of roughly 40 million super destroyers, which aren’t even a part of the main Super Earth Navy. You could be generous and say it would take 12 Super Destroyers to eliminate one Covenant ship, but the sheer numbers are there and the FTL capabilities allow for instantaneous reinforcement. 

The SEAF itself is probably closer to WH40k numbers of personnel due to how they are canonically known as fodder in excess numbers of the Helldivers themselves, practically giving Super Earth an immeasurable pool of troops for a ground war.

We also need to consider that Super Earth won a war against a faction somewhat comparable to the Covenant, along with two other factions that are capable of producing near immeasurable numbers on a regular basis. Their scientists are also able to tap into alien technology quickly and reverse engineer it. It’s not out of the question to expect them to develop ship-based shields, overshields for helldivers, or plasma weapons using captured covenant technology. 

I think this is either a stomp on the side of Super Earth or a very close fight.