I was asked if Scrum per the Scrum Guide was an instance of Kanban. The answer is no because of the differences in the mindset. Scrum (per SG) has immutable roles, artifacts, events, and rules. These guide you to actions that fit within them. Kanban has principles you look at to see what to do. There are other differences in the mindsets of Scrum and Kanban.
However, if you say – “if I take the mindset of Lean can Scrum be thought of an instance of Lean?”, I would suggest that’s a powerful way of looking at Scrum. In fact, that’s what we call “Scrum as Example” (see 1st comment for link). Now “Scrum” is a systems-thinking approach based on flow, explicitly defined work rules, collaboration w/management and ore. I said Lean instead of Kanban because there are several views of Kanban – LKU’s Kanban method as a transition model, most others as an instance of Lean.
The thing to remember is all frameworks are nothing but tools. It’s when we think of them as solutions we get into trouble. and when proponents demand they be adhered to we have dogma. Thinking Scrum is Agile is like thinking the map is the territory. Scrum is a framework, a tool, that can be used to achieve agility (or have a team be agile if you prefer).