How to present results with categories?

CONTEXT
Users are searching for elements called TOTs. All TOTs belong to categories called OTs. Search results are presented as OTs and their associated TOTs. Results are implemented as cards and users can select each TOT to apply an action.

Design of one OT card with 3 TOT inside

DATA
The average number of TOT elements inside an OT category is small - 1.8. Unfortunately, an OT category can sometimes contain up to 20 TOT elements and often contain only 1 TOT. For every search, users will get an average of 100 results. This is a very complex management desktop app for managers and technicians, so results must be clearly presented.

PROBLEM
I feel that there's a much smarter and ergonomic solution to present these search results. Maybe cards inside cards, but this seems wrong to me. What are best practices for presenting categorized search results?

Thanks a lot in advance for your kind help!