"Assigned IP" could mean a few different things.
When I use the term, I only use that for when a system always has a fixed, known IP address.
However, the DHCP protocol (which decades ago I helped develop), is there to "assign" IP addresses for all nodes that don't have one already appointed to them.
Surely EVERY node needs an IP address, and they get that address the one way or the other. As soon as they have such an address, and presuming it's known to the routing systems / software (VPN, "VLAN" or otherwise), then it can communicate anything it wants. What happens from there depends on a lot of other factors such as open ports and so forth...