Tahoe was Unix 03 certified, and is still listed on that page if you filter by standard and choose Unix 03.
Perhaps Golden Gate simply hasn't yet passed certification.
Indeed. And, weirdly, there are items that show up by that 03 standard alongside macOS 26 (e.g. "HP-UX 11i V3 Release B.11.31") that also show on the front page. Is it a latest version kind of thing?
I swear I've seen these "[Latest macOS release] does not appear in UNIX certification site" threads every year since the release of Big Sur in 2020.
It takes several months for the certification to appear on the site. What would be newsworthy is if we see a release next year without this release getting certification.