Use a specific Trigger Action based on CP?

There might not be a way to do it exactly as you are asking.  The closest is to actually create an alert per group instead, where each alert would just have the one action.  The alerts is where you can do the filtering.

Alternatively if the actions are similar you might could do something close.  For example, if all of the actions would be email, then set a custom property to the email address you want to send it to.  So all of the nodes that are in the windows server group would also have another custom property "EMAIL_ON_DOWN" set to serveradmins@mydomain.com, in the email trigger action you would put ${{N=SwisEntity;M=CustomProperties.EMAIL_ON_DOWN}} in the "to" address.  Now every node can have a different email address that it sends it's alert to.  The hard part is populating that custom property the first time, and then keeping it up to date.

Another option is to set the action to "Execute an external program", then run a powershell script to actually do the logic and execute the action based on whatever you can code.

Just create CP "To_notify" (as example) containing email address of recipient (group address of recipients )and use it in alert. Then you can use one alert for all nodes.