Any plans to update this to have icons for categories in the sidebar?
This. Would be great.
It would be great if the category icons worked also in the lefthand sidebar:
I did some modifications on my fork to add support in the sidebar.
I’m not sure this is entirely okay this way, so posting here for now. I would gladly create a PR on the official repo if valid.
To test, install a new component from https://github.com/Arkshine/discourse-category-icons
and provide the branch feature/sidebar-support
(click on the Advanced button)
Note: you will have to fill in your settings again. Don’t forget to disable the official one.

Wow, that’s awesome, thank you!
Sounds like a jolly good idea! Why not put that in anyway now - it will automatically comb your code modifications to ensure it is good on the linting front which can be helpful.
Or do you want to kick the tyres with it a bit more first?
No, Arkshine doesn’t want kick any more tyres
I really would like to see this adopted. Moving all settings here, there and everywhere is lousy job if this could jump in the original one.
Sorry, I forgot to answer here
I posted here for testing purposes and because with some chance someone from the team would validate my modifications.
I made a PR now.
While icons aren’t supported in core (yet?), work has been made toward this kind of customisation: