Is this the same as the Substack App?

No, the Substack App is a separate mobile app featuring all of your Substack hosted
subscriptions, the Notes feed, livestreams and live chat all in one place.

TheBulwark.com and Bulwark+ are hosted on Substack. The Bulwark App is powered by
Substack but only contains Bulwark content. Your Bulwark+/Substack profile grants you access to Bulwark content in any of these spaces.