Power BI Search tool

Beyond the out-of-box search feature, you can potentially pull Power BI admin API data into a report that people can browse. I did this at one point to create somewhat of a report catalog in Power BI.

The admin API has data on # views, reports, dashboards, semantic models, etc - and can pull the description fields for reports. What we did was have a process by which people would actually fill in their report description with relevant keywords, then use the filter pane advanced filter to search on that. Obviously this requires people to be diligent about actually filling that out, which won't happen unless you push it as a part of a process, but on top of that the admin API also has measures and columns metadata so you can potentially search those also. 

Gettin data out of that API is more of a data engineer task that not everyone will want to go to, but it does work.