Do you have any experience with building a computer in the past by chance? It’s not that it’s all that difficult, but if you don’t have much experience, you just need to be comfortable with the fact that you are essentially your own tech department/warranty/repair service if you have any issues...
Since you live in the snow belt/rust/salt region, I would opt for something made from 304. It’ll last through the environment you deal with in NE Ohio. That’s my advice at least. 304 will still get surface rust, but far superior to 409.
just out of curiosity, did you notice if it ever showed your m.2 drives in the bios originally? I see there are some posts about asus boards not showing them in the bios for some people. Anyway, I'm not sure if you know which one has the OS installed? Can you remove the other and see if...