Hi,

Just check this and get an idea : https://www.odoo.chttps://www.odoo.com/forum/help-1/question/how-to-see-all-users-who-are-logged-on-15061om/forum/help-1/question/how-to-see-all-users-who-are-logged-on-15061

For getting the users last active time, you can check with this community module : User Last Active Date

If you have this module, then  you can check the last active time and analyze who are logged in and not.

As is a paid module , if you are not interested to buy it,  just check the def session_gc (http.py) function and try to get the last active time of the users.

Hope this will give you some idea ,

Thanks