[ddhhyy]

In the U.S., a great place to start is the USGS Lidar Explorer: https://apps.nationalmap.gov/lidar-explorer/#/

This site provides access to lidar point clouds (and DEMs, etc) collected by many agencies.

Additional lidar data is often available from individual state agencies, which is sometimes not aggregated into the national-scale services. A good search term is "[state abbreviation] gis" for the state of interest.

AFAIK, OpenTopography merely aggregates the data available at the above sources and similar. Unfortunately, OpenTopography has relatively restrictive access terms (e.g., free access only for those with .edu addresses), even though the same data accessed directly from USGS or other federal agencies has no such restrictions.