Ideal contrast for background and text outline/stroke colors

There are multiple answers on how to achieve the minimum recommended color contrast for a11y purposes on Web pages (one can learn more, for example, here). However, all of them seem to discuss only the contrast between background-color and color. I couldn't find answers regarding the required minimum contrast between text outline (or text stroke, the "border" of a letter, so to say) and background-color.

Below is an example of bad contrast between background-color and text color:

And here is an example of possibly good contrast achieved with text outline (using the webkit-text-stroke CSS rule):

Question

How can I know whether the contrast between the background color and the text outline is good enough for a11y purposes? Or is it never acceptable to use text-outline for contrast (i.e. one should stick only to text colors and background colors)?