The dhcpcd.conf manual states:

     broadcast
             Instructs the DHCP server to broadcast replies back to the client.  Normally this is only set for non-Ethernet interfaces, such as FireWire and InfiniBand.  In most cases, dhcpcd will set this automatically.

Would it be possible to do this for ipvlan interfaces as well?

Unicast packets don't make it through the device unless it's configured. I don't know if this can be worked around, but by design it only demuxes based on layer 3 data.