For AppMon if it is not a supported technology like Java, .NET, etc... you can still just deploy a host monitoring agent to get basic OS level metrics. They also support entering process patterns which can be checked for and alerted upon if they are missing.
Adding to James' answer, you can also achieve some level of monitoring without any agent installed. This is done by configuring "observed tiers". Observed tiers are components like load balancers, or datapower devices, etc. which don't have a specialised agent for their tech but still require monitoring.
You can define them from System Profile -> Observed Tiers, using a combination of hostname/IP, host:port mapping, or destination (if a messaging component).
You can read more about this here: https://www.dynatrace.com/support/doc/appmon/appli...