Similar to chrome://flags, I think it'd be convenient if we were able to do the same with features and params. Specifying values from the command line doesn't easily work for mobile.

I'm not sure if it's possible for iOS, but for Android you either need a chromium checkout and then run build/android/adb_chrome_public_command_line, or install adb and manually edit /data/local/[tmp/]chrome-command-line. For non-engineers this is pretty tall ask.