harry potter - Book or Rowling quote that there are **no** contemporary wizards without muggle ancestors?

I saw this question:

Which pure-blood supremacists were actually half-bloods?

and I was gonna be a smart-alec and answer 'all of them' as there are no actual pure-bloods anymore. However I couldn't find anything to canonically back this up, so I can't be sure. There's the quote from Hagrid in The Chamber of Secrets (film):

Why, there isn’t a wizard alive today that’s not half-blood or less.

Which may be what made me think this. I thought I'd read an author quote backing it up but perhaps I imagined it. Am I mistaken?

Is there any canon (book / JK Rowling / Pottermore sources preferred) confirmation that there are no contemporary, actual pure-blood wizards?

Edit: there’s some confusion so let me clear it. When I say pure blood I mean it literally. No muggle ancestors. 'Pureblood' is defined in Pottermore thus:

The term ‘pure-blood’ refers to a family or individual without Muggle (non-magic) blood. (https://www.pottermore.com/writing-by-jk-rowling/pure-blood)

Answer

In a letter to Lucius Malfoy, explaining why he refused to ban “The Fountain of Fair Fortune”, Dumbledore says that all wizards have some Muggle ancestry.

“So-called pure-blood families maintain their alleged purity by disowning, banishing, or lying about Muggles or Muggle-borns on their family trees. They then attempt to foist their hypocrisy upon the rest of us by asking us to ban works dealing with the truths they deny. There is not a witch or wizard in existence whose blood has not mingled with that of Muggles, and I should therefore consider it both illogical and immoral to remove works dealing with the subject from our students’ store of knowledge.”
_{^{- The Tales of Beedle the Bard}}

Dumbledore, though his intent with his letter was likely at least in part to annoy Lucius, would likely have based his statements in some amount of truth. Some wizards’ blood is of course still purer comparatively than that of other families - for example, the Black family can trace their pure-wizard ancestry through the generations at least to Phineas Nigellus Black.

In addition, a J.K. Rowling writing on Pottermore says there was intermarrying for centuries before the Statute of Secrecy was implemented, so wizards would all have Muggle ancestry. Soon after it was implemented, though, some wizards were already describing themselves as pure-bloods.

As Muggle/wizard marriage had been common for centuries, those now self-describing as pure-bloods were unlikely to have any higher proportion of wizarding ancestors than those who did not. To call oneself a pure-blood was more accurately a declaration of political or social intent (‘I will not marry a Muggle and I consider Muggle/wizard marriage reprehensible’) than a statement of biological fact.
_{^{- Pure-Blood (Pottermore)}}

It’s likely their blood would get ‘purer’ as they continued to only marry other wizards, but they’d already have Muggle ancestry from before the Statute, even if there’s none from after.