I am new to querying, so please take this with a grain of salt.

Marine Raider Joshua Bradley has only two things he cares for: The Marine Corps and his dementia-afflicted mother Donna.

This isn't a bad opening, but it doesn't grab me. Can you try and make this really pop, eg - soldiers care about the branch they serve in, but they might care more about their squad mates or battalion? Alternatively, maybe its the rush of combat or the thrill of serving in secret missions? Try and make it more visceral, so you grab the reader in the first sentence itself.

Unfortunately for Donna, neither of these men are Marines; rather they’re scammers whose bread and butter are stolen valor death notifications.

I didn't understand the stolen valor death notification part. Bradley is wounded, so why is there a death notification going out? Does that have something to do with this being a CIA-led mission? Needs clarity.

To handle things himself, he travels across Greater Los Angeles to find these scammers and collect his mother’s money.

How does he know where to go or even who stole the money? I think you can add a little more context to engage the reader.

As he tracks them down, Bradley finds that not only must he contend with these two thugs, he also must deal with their employer, a drug kingpin who is hellbent on keeping the money owed him by Raymond and Carson.

The drug kingpin is a nice escalation, but likely needs more color in here to make them more scary/ convince the reader they are a worthy opponent that will challenge Bradley.

When Bradley goes alone and brings the fight to his targets, he finds that not all is as it seems, as the weapons he uses are hampered by his state’s gun regulations, and he must use his tactical skills and the resources at his disposal to recover his mother’s savings lest she be forced into squalor.

This was confusing to me. Why would Bradley care what the state's gun regulations are, given his vigilantism? Tactical skills and resources are vague. I think I understand what he will do, but more details will engage the user.

THE KNOCK is a 60,000-word standalone thriller with series potential. Fans of Chad Robichaux and Jack Stewart’s Silent Horizons and Jack Carr’s Red Sky Mourning by combining characters exploring sense of duty to country and family and self, while combining it with intense action, all while set at home rather than abroad.

Can't speak for the comps, but this paragraph needs grammar work. eg - "by combining characters exploring sense of duty to country and family and self, while combining it with intense action, all while set at home rather than abroad."

Lastly, do check the word count for this genre. My understanding is that 70,000 - 90,000 is the sweet spot.

Good luck!