You can import users from .xlsx
Is there a way or tool to import users from an .xlsx file?
wpForo is based on the core WordPress user system. You can use WordPress plugins to import users. here are some example plugins. Just export users from .xlx to .csv and import .csv using one of these plugins:
Once users are imported, go to Dashboard > Forums > Dashboard admin page and click on the [Synch User Profiles] button.