Start by going to apps.splunk.com and searching for the maker of your network devices. It's also possible the vendor has Splunk apps available from its own site so check with your support team.
Actually my main focus is on telecommunication devices, Voice devices/gateways/routers, radio area network etc.
They can generate syslog/trap (i believe).
unfortunately I don't have the list of models but yes, mainly looking for the core telecom devices which are basically used by ISP/telecom provider (like as AT&T, Verizon etc) in LTE/VoLTE to provide voice and data services to the end mobile/broadband users.
like as RAN (Radio Area Network) devices.
I tried to explore splunkbase and found few like NetScout, Netflow etc.