I know plenty of people who get perfect HR readings from their wrist strap. Personally I've always used a chest strap because I want to be able to trust my data.
For recreational runners like myself it doesn't really matter, but the real issue here is WG is publicly stating he is going to set a world record while also being well aware of the scepticism around his run (and this isn't the first time) almost solely due to his dodgy looking HR data.
It's also interesting to note that during the US trans con they claimed it was a tech issue (albeit not willing to do anything about it) whereas now they seem to be saying it's just superior genetics.
For me the HR is one thing, it might just be dodgy data... but for it to be consistently dodgy and only when he needs it to be - thats a red flag for me.
But then there is also his running pedigree not quite adding up, how fresh he looks on his socials, lack of any real adversity.
I've never done anything to this level, but if this were me I'd be doing everything in my power to prove I'm running the entire thing and put the critics to bed.
There can only be a few reasons why he hasn't/won't do that:
A) Something dodgy is going on
B) He's doing it legit but the controversy drives and boosts his engagement (no such thing as bad publicity? (I disagree!))
C) He's an idiot / doesn't care
I can't think of any other reasons why he wouldn't take a few minutes out of his day to put the HR data issue to bed... there are a number of ways he could do it quite simply if he wanted to.
Also one last thing while I'm here - his cadence data is super consistent, almost metronomic. I saw another comment here or on strava saying it didnt match up with any of the clips we have of him runnning on IG/YouTube, might be another area for people to look into.