It’s not for everyone, but as an example, DaisyDisk was the number one app in the Mac App Store last year under the utilities category. There is a demand for this kind of thing—not clear whether there is for my particular implementation of course ;)
If it is for Windows I'd look into putting it in their app store if you haven't already.
You probably need to contact some evangelists and maybe they'll point you in the right track!
They also like to send "success stories" on e-mails and such, aim for something like that!.
Could you say more on what you mean by an “evangelist”? One thing I thought of doing is talking to websites and youtubers who do app reviews, figuring if it got enough attention someone from the Microsoft store might take notice.
They get paid to produce tech demos, give talks, engage with the community, alpha and beta test the latest and greatest tech, etc...
https://careers.microsoft.com/professionals/us/en/c-evangeli....
https://www.youtube.com/watch?v=bJMuh0ZiDZQ
If you connect with people who are Microsoft MVPs, they can probably put you in touch with them. I think engaging with some through Twitter would be the way to go.