Is it possible to manually initiate agent based policy, either in console or via API?
How long does it take assets in group to reflect under agent based policy?
Also, is it possible to create template and site to certain policy against assets with agents?
Agent based policy scanning is not something that can be done ad-hoc. When you enable a policy for agent based policy scanning it goes into a queue that revolves every 24 hours performing the assessment on those assets.
If you’re looking for ad-hoc policy scanning you would need to use the scan engine and a policy template. This of course requires authentication so either username:pass or the scan assistant.
And of course, if your target is a remote desktop not connected to the network then you can’t scan with the engine so the only option is to wait for the policy to re-assess the asset on it’s 24 hour interval.