Maintenance Window settings is already available to all users with Change Monitoring permission level to some MZ since version 1.231 (https://www.dynatrace.com/support/help/shortlink/release-notes-saas-sprint-231#problem-detection-and...), SaaS, not sure about Managed.
The users need to be part of the MZ used on the Maintenance Window filter, in order to be available to them.
Can you provide more details about your case? Are you on SaaS or Managed, on which version?
Are your Maintenance Windows using the MZ filters?
How are the users permissions defined?
In the UI it is currently not possible to give access just to the maintenance winow section of the settings. The user would need to have complete settings permissions.
If API access is fine, you can generate a token for the user that has only the requiered scope for maintenance windows.
you can leverage Policy Bindings to remove settings access. Currently we only allow the users to see the ability to set a maintenance window, and we also link their Management Zone to the users which then in turn they can only set a Maintenance window to those entities in the MZs they have access to