Board Thread:Support Requests - Designing Your Wiki/@comment-4530178-20190717112234/@comment-9605025-20190717210630

Not that I know of. Plus, I think it would be in violation of the customization policy (see "Changes to the local navigation, page header and article header" in the examples table). According to the policy, local navigation can be customized only though the provided tools such as ThemeDesigner and MediaWiki:Wiki-navigation. There are only two listed exceptions; neither or which are what you are trying to do.