What is the best/modern alternative to Sample(Indexed)Primvar for fetching time-sampled camera data (e.g., for blurring due to focal length animation)?
We’re currently one of these “legacy users” 
Sample(Indexed)Primvar should still work, right? (If not, let me know). On the render delegate side that’s probably the right approach for the moment, although you can bypass backend emulation and get the datasource of the prim you are syncing via renderIndex->GetTerminalSceneIndex()->GetPrim(GetId()), and just interact with hydra 2 directly that way.
Yes, we have things working continuing to go through this interface. There’s a bit of a wrinkle that in Hydra 1 we get raw camera-unit values and in Hydra 2 we go through a scaling data-source and get world-unit values, so we’ve had to add logic to the render delegate to check the Hydra “mode”, but it works. Just wondered if there was something we should be migrating to (other than, of course, direct Scene Index interaction).