UnHackMe is a file scanner -- many of the big anti malware software companies offer similar as standalone apps, and they have their purpose, e.g. some are designed to boot the device into a WinPE or Linux environment to scan files without Windows running. That may pick up malware and related files that can't be seen in a corrupted copy of Windows. That said, malware developers have worked for decades [ever since there were computer viruses] to keep their malware hidden, so scans won't/can't find them. UnHackMe in a nutshell may or may not help, and like other virus scanners, *may* actually increase your attack surface... Security software often sends its roots deep in Windows, in an attempt to prevent malware from disabling it, the downside being that if it is compromised, malware developers love to exploit that high level of privilege.
That's Not to say virus scans are always useless. Malware does come in all shapes and sizes, varying widely in their technical sophistication. You're not going to be hit with something like the SolarWinds hack, which was/is world class -- Microsoft said they identified about 45 companies that had been targeted and compromised, out of thousands that installed the update with its backdoor. People with those level of skills are not going to waste their time, and risk exposure, unless the payoff is going to be worth it. But, those highly advanced tricks and tools do trickle down, and can be packaged for really anyone to use if they want.
So, long story short, UnHackMe *may* be a little bit of a gamble. There's lots of malware & PUAs [Potentially Unwanted Apps] that are not technically advanced, and UnHackMe scans will likely detect and remove them. There's also lots of malware that's unlikely to be detected by any scan -- the cyber criminals behind malware have been known to change their software code multiple times a day, so what was detected that morning won't be after lunch. The only way to catch them is to monitor what's going on in Windows, over the network etc. [heuristics], which is something provided by most security apps, from Defender to McAfee to Bitdefender etc. Running UnHackMe alongside of those apps *should* be fine, as long as you don't get hit with a malware exploit targeting UnHackMe.