Currently, the treemap visualization found on the Host Dashboards comes from the output of
ps auxww. This is not continuously run on your hosts. Instead, it's run once on agent start/restart.
The processes are parsed into the names you see in the Agent in the Processes class, defined in:
Post Agent 5.8 this is done in Gohai, the collector calls this here - https://github.com/DataDog/dd-agent/blob/a956e352d392473a5736ea746b23ad6007896774/checks/collector.py#L813
Currently, the treemap is only supported for process data on a single host dashboard - this may not be reused in other dashboards or for other metrics.
If you're interested in visualizing process data outside of the treemap (and have it continuously updated) you'll need to use the Process Integration. Note that this integration does not support wildcards, so you'll need to explicitly define each process you'd like to monitor. To display process stats, we'd suggest leveraging a toplist, or if you're monitoring a large number of processes across a large number of hosts the heatmap will be best.