The individual software components can be operated together on one system, but separate operation is recommended. In case of shared operation, the resources have to be doubled.
These are minimum requirements. Upgrade the instances with more power so that the software components have more performance reserves.
One observer with the specified resources can take over the monitoring of up to 50 endpoints. For endpoints, note the option to define parallel processing of endpoints. The default setting is "2". Depending on the performance reserves, you can adjust the setting down or up. You also have the option to assign multiple observers to the same region, so that the observers share the monitoring of the endpoints among themselves.