Can we monitor external (outside aws) devices in cloudwatch?

Hi,

yes you can monitor non-AWS resources using CloudWatch. For example, you can use the API or SDK for example to send metrics, logs and/or traces to CloudWatch. You can use the CloudWatch agent to collect and send logs and metrics from a server to CloudWatch (see https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/install-CloudWatch-Agent-on-premise.html).

I find it hard to be more specific without knowing more details about you use case. I hope those indications help you.