Hi,

To achieve both:

    Access to own and department timesheets, and

    Select any employee from the same department in the timesheet entry,

you need to define two separate record rules:

Record Rule on account.analytic.line (Timesheets):

[

  '|',

  ('employee_id.user_id', '=', user.id),

  ('employee_id.department_id.id', '=', user.employee_id.department_id.id)

]

Record Rule on hr.employee (Employee selection in timesheet form):

[('department_id.id', '=', user.employee_id.department_id.id)]

Make sure the user is linked to an employee (hr.employee), and they have the appropriate access rights for Timesheets.

Hope it helps.