TL;DR: All in all, I’d call it, “Bs until proven otherwise.”
(What I can see is that there’s a fair amount of internet scrubbing going on with this one).
Some say he’s bona fide, with “internal Pfizer proof!,” some say not.
Who knows if this bio below is fake? Made by the guy himself, or another:
There’s plenty of reddit rabbit holes on the guy as well 
This guy did some background search on him:
With a reply from another:
Hi Brian, to me it looks like nothing in his bio adds up.
Here are some inconsistencies and strangenesses about all the info on Walker you provided: (I’m of the opinion that he might very well be a fake, so we need to be very very careful - I write for Brownstone https://brownstone.org/author/debbie-lerman/, in case you need my Covid warrior bonafides.)
-
Why all the aliases? I’ve never met a legitimate doctor with so many different name combos
-
In the May 18, 2020 article about Covid treatments, his name as an author is listed without an MD (whereas one of the other authors has it), although he supposedly graduated from Med School in 2018.
-
His date of NYS licensure (which needs to be verified - I’m not going to do that now, but somebody should) is October 2021, right in the middle of when he’s supposed to be working as a consultant at Pfizer. What’s that about?
-
All his research is on urology and is very very basic - not someone a recruiter would look at and consider a candidate for a brilliant research or consulting career. Of course, there the equity and inclusion factor, but still…
-
On the match list from 2018 it says he went to USC, but his resume says UT and Yale, no mention of USC
-
The match list says he matched with a program at Tufts Medical Center and the USNews profile says he did a urology residency there 2018-2020 but his resume says he was a resident at Mass General (a Harvard hospital) June 2018-Nov 2019.
-
Urology residencies are extremely hard to get into and are FIVE YEARS long. https://www.massgeneral.org/urology/education-and-training/harvard-urologic-surgery-residency-program. Did he drop out after a year?
-
The timing of his various academic and professional positions doesn’t add up. On his resume under experience it says 6 years, but he only worked as a consultant starting in November 2021 and had a year of work 2013-2014, presumably before medical school (whichever one he might have attended - or not?)
-
None of the people he follows or who follow him are people of color. You might say this is a racist comment, but in my experience with friends who are in different racial communities, there is usually at least a 50% representation of their own racial group in their social media friend community, and usually much higher.
-
His pinterest profile has nothing that looks like he actually pinned - all totally generic
-
There is absolutely nothing about this guy before 2019 that says top pharma exec in charge or worldwide operations. Highly, highly suspicious.