I'd pluralize category -> categories and display a list of categories with 3-4 posts under each category. Then you can display a category under /categories/processwire or use urlSegments to rename that to /category/processwire.
Or just render category list at /categories with urlSegments and redirect /category to /categories.
What I normally do is keep categories under /blog/categories/. Everything works just fine with no need for urlSegments.
One handy tool when using urlSegments is to hook into Page::path and modify $event->return, so you won't have to manually building urls everywhere you need. You still need to implement urlSegment logic though, changing Page::path is a passive operation, it doesnt change routing behavior
