If "your truth" feels true and "my truth" feels true and both are different, then one or both are false.
So simply speaking "your truth" is not any more powerful than simply speaking "your opinion".
Truth is powerful by virtue of being supported by essential facts and reason. If what we say is false, it's power relies on us adding force or manipulation. We need to add these because what's false has no power on its own.
It takes lots of work to uphold a false claim. That means it's not sustainable for any substantial length of time or scale. Truth is powerful on its own.
Despite what Oprah says she knows for sure, speaking "your truth" or "my truth" that's "true" simply and only because it "feels true" is not a powerful tool.