Yes, this is achievable in Insights using Aggregate Property per User on your category property.
1. In an Insights report, select your “page view” event.
2. For the measurement, choose Aggregate Property per User → Distinct count. [Aggregate per user]
3. When prompted for the property, select category.
4. Leave the aggregation as Average to see the average number of unique categories per user, or switch to Distribution to see how many users fall into “1 category”, “2 categories”, etc. [Measurements; Additional examples]
This setup computes, for each user, the number of distinct category values they’ve seen, and then lets you analyze that per-user distribution.