If I have for example aqara smart plug, does it work as zigbee repeater?
And if yes - does it work only for zigbee version it was made for or for newest like 3.0 also?
And does it works between different ecosystems for example if smart plug is paired with aqara hub camera g3, does it also amplify and repeat signal from other zigbee devices but connected to home assistant and working separately not in ecosystem of aqara hub?
The term is “router” not “repeater”.
Yes, probably. Most mains-powered devices act as routers - there is a short list of exceptions here and these are mostly switches. There is a database of devices here that is quite useful.
Zigbee 3.0 is supposed to be backwardly compatible, so if you have a 3.0 co-ordinator a 2.0 smart plug should still work and act as a router. Best to get 3.0 if you can, though.
If you have a co-ordinator that is not part of a particular manufacturer’s ecosystem (such as SkyConnect) it should be able to connect to a variety of devices. If you have a particular manufacturer’s hub (like Philips Hue) it probably won’t. As long as you have a general-purpose co-ordinator, routers from different manufacturers should still talk to one another.
Bear in mind that not all manufacturers implement the zigbee specification properly. The database mentioned earlier includes information about whether devices are known to work with HA.
A Zigbee device can only be connected to 1 coordinator, and be part of the 1 Zigbee network created by that coordinator. If your plug is connected to the aqara hub camera g3, it will NOT route for devices connected to another coordinator, e.g. your Zigbee dongle
Yes, sorry. Misunderstood that part of the question. 