Wayfinder is a universal discovery service - i.e. it is not limited to any single federation, but works for just about all of them.
For the end-user it provides a consistent discovery experience over all the resources that use it. See also: OpenAthens Wayfinder UX
For service providers it provides a discovery service that works for as many SAML federations as the service provider is a member of - there is no need to maintain your own discovery service and no need to present potentially confusing choices to the end user. Wayfinder automatically filters for only the IdPs in the same federation(s) as the referring service provider. See also: Enabling OpenAthens Wayfinder