Agile's one of the best things to happen to software in a way: it's good to know your competitors are stuck in ceremonies, arguing over story points.
The guide also mentions the backlog refinement: “ This is an ongoing activity to add details, such as a description, order, and size.” It’s true that scrum doesn’t directly mention story points but tell me whether story points or t-shirt sizing aren’t the two most common ways to size a story.
Those are "Events", activities to support development work. Unless you mean programming, testing, discussions, code reviews, etc are ceremonies as well?
> It’s true that scrum doesn’t directly mention story points but tell me whether story points or t-shirt sizing aren’t the two most common ways to size a story.
Borrowing your own words: "...story points aren’t in any way mandated by the..." Scrum Guide.
Keep what works for you, leave what doesn't.