I’m not sure whether that answers it or not. I’d assumed that the g/w gave me a bunch of ZWave devices on IP addresses with an API that allowed software to query/update the devices, possibly on a different IP end point. IP is a layer 3 protocol, so it’s not really bridged, it’s routed.
The IP model assumes that all nodes on a different layer 2 network operate at with similar service quality characteristics (throughput, response times, etc) and so the IETF is moving towards using routeing as the mechanism for keeping such networks apart: you don’t want your IoT stuff and your video streaming on the same physical network, or you’ll either run-down your batteries of have very poor video.
However, setting up such routeing in IPv4 has been too complex for home use at scale, so an IETF working group (Homenet) is looking at how to combine the IP routing, naming, etc protocols so that domestic networks ‘just work’.In IPv6, I think that the relevant protocols include dhcpv6 (for PD to subnets), babel (for routeing information - eg to handle loops) and some dns stuff (eg allocation of tld).
For my situation simple integration into such a model is useful as it reduces engineering and operational costs and makes it much easier to create peripatetic code and to combine devices on different network types (eg so that events from my zwave sensors can influence the behaviour of bluetooth, zigbee and 5G connected actuators).
Does that make sense?