WordPress is a mature free code project with a huge user base. Getting fediverse integration for comments working smoothly in WordPress would be a coup. There are a number of plug-ins that provide some pieces of the puzzle, but it might require a bit of community facilitation to herd all these cats into working on one plug-in (or suite of plug-ins?) that does a good job of everything.
WordPress plug-ins that may be relevant
Listed in order of most recent commits (at time of writing):