Explanation:

Step 1 - Scenario
The requirement is to ensure Microsoft Purview Insider Risk Management can collect signals when a user copies files to a USB device using their default browser. The devices differ by browser type:
Device1 # Default browser = Microsoft Edge
Device2 # Default browser = Google Chrome
Step 2 - Signal collection methods in Insider Risk Management
Insider Risk Management uses Microsoft Purview Information Protection client and Purview browser extensions to collect activity signals.
For Microsoft Edge (Chromium-based), insider risk signals are collected via the Microsoft Purview Information Protection client.
For Google Chrome, signals are collected through the Microsoft Purview extension (available in the Chrome Web Store).
The Microsoft Defender Browser Protection extension is for web protection against malicious sites, not for insider risk activity signals, so it is irrelevant here.
Step 3 - Microsoft Reference
Microsoft documentation:
"For insider risk signals collection in Microsoft Edge, the Microsoft Purview client must be deployed. For Google Chrome, the Microsoft Purview extension is required." Reference: Insider risk management activity signals