Render to Canvas node is still there. We only added Opacity input. If you try to open one of the Sample projects in the Basic category, you’ll be able to see it.
You are probably looking at a 2D or a 3D Scene layer, which are different than Regular layers. Each of these 3 types of layers has some unique nodes that are available only to them. For example, Render to Canvas is available only in Regular layers, a Helper plane node is available only in 3D Scene layers. etc.
p.s. this reminds me of an idea of color coding the layers, which was pushed back a bit.