or the Zheng He, supposedly the most advanced and dangerous ship in Starfleet, along with its endless clones. DId it even show up in Season 3 at all?
It did in the fleet scenes. It was there.
The Inquiry class in season 1's garbage model was made by another VFX house at the last minute. WHen the ship was made for Star Trek Online, they fixed a lot of the problems with the ship's shape, textures and shaders, and in the end the game ship ended up being higher quality than the season 1 CGI. When they needed fleet ships for Season 2, not only did they pull in those Star Trek Online ships, but they also used its version of the Inquiry model (not the original), and the new VFX house took that model and made significant changes. THey adjusted the pylons and nacelles, the texturing, and most significantly god rid of the grille on the deflector and changed the deflector's shape. It produced a much better looking starship (this revised version is not yet in Star Trek Online).
It is this "Inquiry 3.0" also showed up in Season 3"
These practice of using video game assets for fleet scenes has an interesting production parallel of sorts. The "Battle of Sector 001" ships made by ILM were of such low quality because of their purpose built "distance viewing" for fleet scenes, that when given to Foundation Imaging (I think) for DS9, they had to be entirely rebuilt in higher resolution for DS9 so closer-ups (not necessarily close ups, just closer than First Contact) looked good. The Norway-class wasn't used on DS9 for this reason. It wasn't upgraded.
Later on, when Eaglemoss was making the art for the books and the source model for the Starship collection, they got those meshes from Foundation's archive, long thought lost, but found on a former artists' server. Their artists redid them up to modern "hero ship" CGI standards for the first time, that added a lot of essential star trek ship detail. These "real versions" of the Battle of Sector 001 ships eventually made it to Star Trek Online over the last few years to replace the lower resolution legacy models (which were often replacements of an even older version). In turn, for Season 2 (mostly) and Season 3 (less so), it is these "Version 3.0" Star Trek Online models, the direct descendants of the ILM ships from First Contact, that had jumped from film, to TV, to book/diecast model to video game, that were used.
In 2022/2023, unless you're getting up real close to a ship for a long period of time, a modern video game model with some shader improvements and good lighting is perfectly sufficient for a 4k TV show.
We've come a long way since Star Trek Armada.