Start Chromium at web page with ActivityManager

I've got Chromium 106 installed on my phone and can successfully launch it via

$ adb shell am start -n org.chromium.chrome/com.google.android.apps.chrome.Main

However, when I try to bring up a specific page at launch time with

$ adb shell am start -n org.chromium.chrome/com.google.android.apps.chrome.Main -d http://127.0.0.1:8080 

(I've got a web server running on port 8080 on my host with reverse TCP forwarding set up.) the app doesn't launch but I get the error

Starting: Intent { dat=http://127.0.0.1:8080  cmp=org.chromium.chrome/com.google.android.apps.chrome.Main }
Error type 3
Error: Activity class {org.chromium.chrome/com.google.android.apps.chrome.Main} does not exist.

Is this not the right way to use am with Chromium? Note: The command works if I run under su -c.