Let's move straight to the point or question.
Can I use both APIs 3.x, and 4.x as part of the same app?
On my work, we have a website made with ArcGIS 4.x. I was asking to add a FeatureTable but that widget does not exist in 4.x yet.
I know I can use different ways like, for instance, "dgrid", but implement that solution consume more time and effort.
So if I can refer to version 3.x I am going to be able to use "esri/dijit/FeatureTable".