But it's also possible without "middleware" by using a Restlet on NetSuite end, and a Google App Script

I’m interested in existing and preferably supported solutions. I’m able to build something, or we could hire other people to build, but in this case I’m fairly sure there are extant solutions. When it comes to build vs. buy, I fall on the side of “let’s not reinvent the wheel.” I’m hoping to get in touch with someone who is actively using a NetSuite-to-Google Sheets solution.

Got you, I haven't heard of anything existent.