That could be because you're not writing your tables properly... though I have zero clue what you mean by "pinned" or "virtualization". By "pinned" do you mean position:sticky?
But take your litlte demo snippet, It's bad enough trying to figure you what the *** you seem to think you need canvas for there... but pissing the stupid pointless aria role nonsense--that does nothing in any legitimate non-visual UA--even worse.
Where's your TBODY? What possible purpose does "indexing" your rows accomplish? Shouldn't that first TD be a TH set to scope="row"? Where's your THEAD with TH scope="col" to describe the columns negating the need for the aria bloat?
It looks to me like you're getting canvas and a bunch of scripting involved because you don't know how to use proper HTML semantics in building tables. Or how to manipulate the DOM for things like sorting. OR how non-visual accessibility is suppsed to be implemented.
Though it is really nice to see someone using canvas (for nothing probably) at least trying to provide the fallback content.
That said, given the accessibility wreck and middle finger to UX that "Glide Data Grid" site is, I'm shocked one would even bother. Illegible white on light / sky blue, absurdly undersized fixed metric fonts, use of PX flipping the bird at users with accessibility needs, issues with the scrollbar focus making scrolling the site difficult because of the garbege use of CANVAS for what should be normal data...
I mean just to show what I mean in terms of overthinking the problems you're throwing canvas at...