The first second release of this tool lets you rename the players and town in an AC:NH save. It's rather simple, so make sure you're aware of the backups created in the bak-#### folder.
It will try to find your Ryujinx AC:NH save automatically.
In future, this should be more aware of the direct places where the ID+Name combos are present, rather than find replacing through the data like the NHSE ChangeIdentity function does.
If you're on linux for whatever reason, you can run the exe under mono.