Change #1203874 had a related patch set uploaded (by SD0001; author: SD0001):

[mediawiki/extensions/Scribunto@master] Sanitize SVGs and allow embedding as <svg> tags in HTML

https://gerrit.wikimedia.org/r/1203874

Change #1203875 had a related patch set uploaded (by SD0001; author: SD0001):

[mediawiki/extensions/Scribunto@master] Support advanced elements and attributes in SVG sanitizer

https://gerrit.wikimedia.org/r/1203875

The best actual use for it isn’t even necessarily interactivity but the ability to use CSS on SVG contents. As we are currently providing the night mode by default to all readers, this is incredibly important even if there was zero interactivity, as an SVG in base URI would have to be either given a white background or reproduced twice to work in night mode. Either way, not the best.

In T407783#11990940, @stjn wrote:

The best actual use for it isn’t even necessarily interactivity but the ability to use CSS on SVG contents. As we are currently providing the night mode by default to all readers, this is incredibly important even if there was zero interactivity, as an SVG in base URI would have to be either given a white background or reproduced twice to work in night mode. Either way, not the best.

Note that <img> tag svgs do support night mode (at least in some browsers, havent tested in all). The biggest issue is we cant use css variables in them so its a bit annoying and not skin-agnostic.

On plwiki we recently created a template for that:

{{Theme
  |light = [[File:Light image.svg|thumb]]
  |dark  = [[File:Dark image.svg|thumb]]
}}

Not great, as it;s almost twice the work, but it works.

Still, both CSS support and SVG interactivity would greatly improve the experience for both editors and readers (edUX and readUX 😉).