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.