@ian10 I believe the development of this is on pause as there are issues with the current app version:

Dark Mode on Mobile - Instructure Community

Some institution's colors are not working for dark mode and accessibility (or access at all) as there no longer is enough color contrast to see links to some items.  Based on the blog, I think they are getting feedback from users and that might be a path toward how a web version is created.  I have not been told about a web version in the works but just assuming they will not want to develop it until the current issues with the app version are addressed.

-Nick