Honestly, any place that won't hire you for being a WOC is a place that you wouldn't want to work for anyway. As for being a woman in IT, don't think about the people who would look down on you for your gender and focus on being the best tech you can be. I've worked with numerous POC and women, and outside of noting race/gender at the beginning of an interaction, people worth their salt don't give a shit about that as long as you can pull your weight and get the job done.
Regarding powershell, look into the book "learn powershell in a month of lunches" or something like that. Will give you a good base to build off of. Then from there, find excuses to shoehorn it into stuff you're doing at home, as that's the best way imo to really learn a language. For example, one of the big projects I wrote was a massive powershell script to scan my media intake folders and automatically convert files to the standard settings I use for my library.
For your last point, I can't really give you any meaningful advice because even after my time in the industry and the praise I get from my management and peers I still struggle with feeling like I'm too dumb to figure something out or I'm just pretending to be good at my job. Imposter syndrome is just something you get used to after a while.
minnieo