I'm on the east coast myself, in my 40s, also tech (mostly hardware/design, but some software in support of that hw or just doing something experimental).

I will 100% show up with a T-shirt, jeans, and sneakers. If I have a meeting or its the fall/spring, I have a sportjacket, but I've admittedly shown up in a zip up hoodie before (though that was specifically in a space I was doing some concepting in, not a boardroom).

Client meetings with their c-suite will get a collar, but its a golf shirt in the summer.

That said, I work from home pretty much exclusively, so its all t-shirts now. I wouldn't even worry about straight up Donald Duck'ing it if it were more comfortable (its not).

I think its just generational.