Hi Aditi,
Yes: In larger enterprises, a single sign-on solution (such as ForgeRock, Okta, etc.) is typically implemented. If the users have already been authenticated and use the standard Maximo URL (e.g., https://maximo.xyz.com), they will be taken directly to the start center, provided they haven't set up their own screen preferences.
No: The JSESSIONID is a temporary session token and won't be useful for this purpose. You cannot use the REST API to authenticate over the browser, even if you pass the login token in the API URL.