A category can define tags that get special styling, like bug/discussion/feature-request/support here on meta. (It's one special style, not different styles for different groups of tags.) So Q&A could make code-review stand out like that, along with any other future tags that should be treated specially. // A new category can share a tag set with Q&A, meaning that searching by tags would show posts from both categories. But different categories means different question lists.

@Monica Cellio Can each category get custom close reasons? See the discussion in comments below my posted answer.

I agree. I think code review questions should not be in their own site, they belong right with all the other software development questions unless it should prove to be completely unworkable.

Tangent, but I don't have another way to contact you: Alexei, you're pretty active here, so I want to make sure you're aware of https://software.codidact.com/questions/278470. Interested?

For what it's worth, while it looks reasonable at first glance, my experience is that at least Somewhere Else, using tags to segregate types of content (specifically in the case I have in mind, different requirements placed on answers) has worked poorly in practice. A separate category seems likely to work out better, even (or maybe especially) if it is low traffic.