I have been using the call screening feature on my Original Pixel for months now. It works very well. I can't comment on making reservations via phone, since we don't often go to places that require reservations, but the call screening is great.

You've made this claim a few times in this thread now. Can you please elaborate as to what about Duplex, specifically, has not worked for you?

Edit: A quick browse through OP's comment history suggests that s/he might not be US-based. Should that be the case, then it's not that Duplex is flawed, it's that it's simply not available where they live.