I seriously doubt either Intel or AMD ship different silicon to the NSA or whoever else. At least from what I've read, the only difference (at least on Intel) is the "NSA bit", that can actually be turned on on any chip these days. System76 actually ships machines with it enabled by default.
If you're going through all that effort, then why bothering with hardening Chrome? Why wouldn't you start with Firefox, which doesn't require unGoogling to be considered secure?
OpenBSD's Chrome had pledge() first, but you're right, I should consider Firefox.
However, there was a recent Firefox bug in OpenBSD, and the patches weren't applied uniformly. It does seem that Chrome is more consistent, and gets more attention.
