I am also currently wondering if adding focusable="false" to the <svg> elements could be useful since it may cause an accessibility issue in Internet Explorer?

title technically provides an accessible description, rather than an accessible name.

maybe a slicker way around it is to add aria-label to the <button> - then you can save yourself the aria-hidden="true" on the internal svg as well, since the aria-label on the parent will completely replace/override whatever's inside the button anyway?

<button ... aria-label="Try" title="Try it on StackBlitz">
  <svg class="bi"><use xlink:href="#lightning-charge-fill"/></svg>
</button>

as for focusable="false", not sure if we still need to cater to IE since it's now been officially deprecated by Microsoft, and that was the only browser exhibiting this odd behaviour.

also, note that

Svgs inside 'Try it on StackBlitz' and 'Copy to clipboard' buttons are pure decoration so they must be ignored by any assistive technology.

is perhaps not completely accurate. They're not pure decoration, they represent the content/label of the button... but that's probably splitting hairs

<button ... aria-label="Try" title="Try it on StackBlitz">
  <svg class="bi"><use xlink:href="#lightning-charge-fill"/></svg>
</button>

Ok with your version and for your opinion about focusable="false" since IE is not listed anymore in the list of supported browsers on .browserslistrc file

However I think it will be better to keep the same content in the two attributes:

<button ... aria-label="Try it on StackBlitz" title="Try it on StackBlitz">
  <svg class="bi"><use xlink:href="#lightning-charge-fill"/></svg>
</button>

depending on browser/assistive technology used, both the accessible name and description may be announced, resulting in an overly verbose announcement (though, at least with Chrome/NVDA and Chrome/Jaws, it seems that if both are exactly the same, it's only announced once). Will test some more later just to check...

title technically provides an accessible description, rather than an accessible name.

I've actually just tested it, and it seems that consistently browsers use/expose title as an accessible name if it's the only thing present, rather than using it as a description

Long story short, after more testing (also in Firefox/Win and Safari/macOS), ignore my suggestion. This will be fine as is ;)

also, i'd note that those buttons were accessible even before this, but they did lead to an unnecessarily verbose announcement (along the lines of "image Try it, button, Try it on StackBlitz"). so this PR is more of a nice tweak ("Try it on StackBlitz, button")