The First Amendment does not have the same restrictions as the Second Amendment.

To the extent that your speech does not also constitute illegal action, there are no restrictions on speech and those protections do not depend on nationality, citizenship, etc. All that matters is the jurisdiction of the US court system (since they can't enforce First Amendment rights if they don't have jurisdiction).

Some types of speech are also acts, like conspiring to commit a crime, or inciting violent action. In those cases, the content of the speech is protected, but the actions of the speech are subject to prosecution.