Jenner claimed to have undergone "the full surgery" in January 2017 in Jenner's book and in a highly-publicized longform interview with Diane Sawyer for the ABC television program "20/20." But that doesn't mean Jenner actually had genital surgery to make Jenner's "pee pee" and testicles go "bye bye" as you'd put it.
The few times Jenner publicly spoke of the matter back in 2017, Jenner always made a point of using the most vague terms possible - "the full surgery," "complete gender confirmation," "the surgery," "living as a female," "for all intents and purposes I am fully a woman" - then would immediately change or drop the subject.
Jenner told Diane Sawyer in 2017:
“I do mention in the book everything I did. But I wasn’t less of a woman the day before I had the surgery than I was the day after I had the surgery... [And mentiong "the surgery in the book] doesn’t mean in the future that I have to talk about it, that I’m going to dwell. The media may but I’m not going to dwell on that subject. And I would make a suggestion to all people out there -- don’t ask the question. It’s not an appropriate question to ask any transperson.”
A few years later during a televised roast of another male celebrity - a Hollywood comedian, IIRC - Jenner used Jenner's time at the podium to quip, "I didn't really cut if off. I just retired it."
So I'd take the claims Jenner made in 2017 with a grain of salt.
BTW, a lot of prominent trans-identified males have claimed to have had so-called "sex change" surgeries on their genitals when they haven't.
For example, American social media stars Gigi Gorgeous and Blaire White - each of whom has millions of subscribers on YouTube and other platforms - both made these claims when they first started becoming famous for being trans. But later on, both made videos confessing that they actually still had all their original male parts and revealing they were trying and hoping to be able to generate enough viable sperm to father children.
Gorgeous has since reported success on YouTube, other online platforms and in mainstream media appearances. In a frank YT video, Gorgeous says that after going off T suppressants and giving up the practice of "tucking," Gorgeous was able to produce enough viable sperm to have a child through IVF with Gorgeous' spouse, Nats Getty. (Getty, one of the heirs to the Getty oil fortune who has struggled with heroin and alcohol addiction since early adolescence, became a so-called transman since hooking up with Gorgeous.) Gorgeous says the couple has several more IVF embryos on ice.
Sadly for Blaire White, White's efforts to recoup fertility didn't go as swimmingly as Gigi Gorgeous' did.