Are there any yc companies that would really benefit from your company? Reach out to them and ask them for feedback and explain that you chose them because you believe they understand the problem because they experience it.
We're working on cloud automation using NLP, so anyone with cloud infrastructure would benefit from it. But I see your point. Thanks for the advise.
I just did research, found them on their websites and emailed whatever public address I could find. Be direct, these are busy people so they dont want to read your life story when you are just asking them to review. Also, be ready to share your application - even go so far as giving them a sharing link to a Google doc with your questions and answers in it. If they have to say 'sure, I will take a look' and then wait for you to respond you may miss the window.
In case you are wondering I emailed about 30 people and 8 reviewed our application. Most did cursory reviews and offered some changes and a few paragraphs of advice while others really got into helping us - it was quite the gift.
Just ask! No one will think it's spam.
Be authentic in what you write. Spam mostly sounds the way it does because it's lying to you.