I was hoping I could get Jspoiler enabled/added.
Jspoiler per: https://www.mediawiki.org/wiki/Extension:JSpoiler
Unfortunately, we do not have this extension installed on Miraheze Servers, so it will have to go through a security review.
Not in a Git repository thus declined.
The code is right on the page?
https://www.mediawiki.org/wiki/Extension:Spoilers Here's one on git.
The extension itself looks pretty simple (easy to add), although you may want to consider built in collapsible elements.
Per talk internally, the extension is basically js and also per @Void suggestion.