RKE (their Kubernetes deployment and management platform, mostly for various flavours of self managed environments) is pretty popular with the self-managed crowd that needs something to manage their on Orem Kubernetes clusters.
That's why I wrote Rancher side products.
(Former employee) They tend to either get enough traction very quickly and be supported for years, or not and be abandoned in weeks/months.
This is not a side product but it's currently GA and part of the Rancher Prime offering. :)