I would like to control all my smart devices from a single hub instead of needing to go from hub to hub to control each device.
1. Is it possible to connect the Hubitat C-8 Pro model to devices such as the Aqara Smart Lock U100, Aqara Video Doorbell G4, and Eufy Indoor Camera E220?
2. If so, would I need the respective hubs for each company (Aqara & Eufy) to connect the devices to the Hubitat Elevation (HE), or can the Hubitat connect directly to each device for remote control without the need for the other hubs?
3. If it is not possible to connect these devices directly to the Hubitat C-8 Pro, with or without the other hubs from each company, what options do I have?
Many of these third party systems are all cloud based, so there is no effort by HE to create integrations. They typically go for local integrations.
For Eufy, here is a recent topic, there is no HE solution but there is something for HA: Hubitat integration with Eufy app
For Aqara, I think they possibly have a Matter bridge hub? With that you could potentially bring some devices over to HE via Matter using the community build Matter bridge driver. Matter does not support all device types and attributes yet though.
What are you trying to do with cameras anyway? You cannot do anything useful with a video feed in HE. About the only thing you could do is get motion alerts from the cam, or possibly start/stop recording from the hub.