Confirmed canon in Deadpool & Wolverine
The post-credits scene from Deadpool 2 has been officially confirmed as canon in the latest installment of the franchise, Deadpool & Wolverine (2024), which takes place in the Marvel Cinematic Universe. The film itself is the fulfillment of Deadpool's promise to Wolverine in the post-credits scene, as he indeed asks his "old pal" to "get back in the saddle again."
In this film, both Vanessa and Peter are shown to be alive, validating Deadpool's time-traveling escapades from the previous movie's end credits. Moreover, the Time Variance Authority (TVA), an organization responsible for maintaining the "Sacred Timeline," explicitly acknowledges Deadpool's use of Cable's time machine.
To further cement the canonicity of these events, Deadpool & Wolverine even includes footage from the Deadpool 2 post-credits scenes, seamlessly integrating them into the main continuity of the franchise.