If you want to just host the wiki in read-only mode you can use anything that works as a static file server, I only used flask once for a tiny project, so I don't know the specifics.
If you want to run the server version of tiddlywiki it is written in node so you would have to rewrite the entire thing in python if you want to use that with flask.
If you just want a python back-end that can save your wikis instead of using php that wouldn't be too difficult, it just has to accept a POST that contains the wiki and saving credentials and save the file to the file system.
I made the BobSaver plugin, it is designed to work on the local machine so it doesn't have much in the way of security, but I made node, Julia and python scripts that can be used as the server, so it may help.
There are other savers people have made, but I don't remember any names.