Porting MoinMoin 1.x to Python 3.x would be a major hurdle especially since MoinMoin is very complex and has lots of advanced features (from supporting multiple syntaxes to API and even master-master replication). (On the bright side, by default it doesn't seem to have many dependencies, thus at least in that regard it would be easier.)

Therefore if I were to invest development time into a wiki engine, I would definitively go with a simpler Rust / Go based implementation from scratch.

In fact this is another reason why I'm looking for alternatives, namely I want a "simpler" wiki.