Depends on your networking setup. A good switch will simply refuse to route packets between clients on different VLANs, and hide the existence of the tags that determine which VLAN a host is on.
A bad switch or router (which almost certainly includes a ton of crappy home APs and routers, compromised by the same actors who ship these devices) could let clients see VLAN tags and ignore them.
And an Ethernet “hub” does no filtering at all.
Also: if you need a streaming box to see your AirPlay or UPnP devices for “casting” it necessarily has to be on the same VLAN as the devices it’s connecting to. Sonos speakers have this problem when subject to client isolation setups based on VLANs or switch-level packet filters.
And any kind of multicast (used for local service discovery and media streaming) has the same limitations.