Got it. Thanks for clarifying. In Classic Outlook 365, desktop alerts are triggered for all incoming messages in your Inbox, including messages that may be redirected by rules, but not for Junk folder messages unless a rule moves them there. If alerts are showing for Other or Junk, check:
Your rules under Home > Rules. Some rules moving messages may trigger alerts.
Focused Inbox is enabled; alerts should normally only trigger for Focused messages.
Junk folder settings; messages marked as Junk should not trigger alerts unless manually moved.
Microsoft does not provide a built-in option to limit alerts strictly to Focused folder in Classic Outlook 365.