You Must Use The Following Flow Chart when You develop Appliction or Use The Api End points in other System.Only Four Api Endpoints Using Without Request Access Token :/api/PublicGeneral/GetLocaleStringResources
/api/PublicGeneral/GetSettings
/api/PublicCustomer/GetGuestToken
For above mentioned methods you just need the application API key You can Check Login setting by request /api/PublicCustomer/GetLogin api parameter to get all login detail and setting.it has one checkoutasquest as parameter to check if quest is can check out or not.
The Api Endpoint Get Login Model not required it's only get login setting So you can check what is enabled and whats is disabled and other setting,also you check if quest can chckout or not.