It was only a week ago that security researcher iBSparkes teased the Cydia package manager running on an iPhone with the first developer beta of iOS 13 installed on it, but as it would seem, that was just the tip of the iceberg.
Apple deployed the second developer beta of iOS 13 just yesterday afternoon, and a new teaser shared just this morning by security researcher and Yalu jailbreak developer Luca Todesco appears to show a working tfp0 exploit running on it: