Wide Area Bonjour (which is a combination of local area and using DNAC as mDNS controller) can support any kind of mDNS application, not only Apple.
Chromecast uses the _googlecast._tcp.local. service string, when you deploy Wide Area Bonjour, you first configure the Edges as mDNS gateways or "SDGs" to snoop the services you want, for example:
(You can get the full config from https://www.cisco.com/c/en/us/td/docs/cloud-systems-management/network-automation-and-management/dna-center/1-3-1-0/user_guide/cisco_dna_service_for_bonjour/b_cisco-dna-service-for-bonjour_user_guide_2-1-2/m_automate_policies_through_template_editor_...)
mdns-sd service-list INGRESS-SERVICE-LIST IN
match google-chromecast
mdns-sd service-list EGRESS-SERVICE-LIST OUT
match google-chromecast
mdns-sd service-list WIDE-AREA-SERVICE-LIST OUT
match google-chromecast
Edge1#show mdns service-definition name google-chromecast
Service Type PTR
=======================================================================================
google-chromecast built-in _googlecast._tcp.local
The whole wide area bonjour solution uses Local Area Bonjour (which is the traditional mDNS gateway feature) to locally process mDNS queries and advertisements on the same switch in different vlans (or same vlans in unicast bonjour in 17.3.1 and onwards). But for a fabric, when mDNS devices are separated across Edges, instead of relying in L2 flooding, which can't control the scope of discovered devices, the DNAC can act as a control plane for mDNS queries across Edges.
Wide Area Bonjour on DNAC can also support non-Apple mDNS like chromecast, but you will need to create the service type on the GUI and assign it to a service filter:
The current best practice for fabrics is to use mDNS in unicast mode (which requires 17.3.1 and onwards), which is enabling the SDG gateway on the vlan itself instead of the SVI of the edge nodes.
