Is it really that hard to just check for the WEI feature directly instead of checking to see if the user agent is Chrome's? There are going to be non-chrome users spoofing their user agent as Chrome, or people using Chromium forks that don't include WEI. Leave them alone.
wei implements an visible function in n'the navigator object: getEnvironmentIntegrity. Testing on the existence of the function should be enough to see if wei works.
Is it really that hard to just check for the WEI feature directly instead of checking to see if the user agent is Chrome's? There are going to be non-chrome users spoofing their user agent as Chrome, or people using Chromium forks that don't include WEI. Leave them alone.