list products in same category

I have two tables, Products and Categories (many products => one category).  My report is filtered on Product.

I want to create a calculated table to view the competing products (i.e. the other products in the same category).  Eventually I will rank them by sales, etc, but for now, I'm just piecing it together.

My first step was to create a DAX measure to give me the count of the competitors, this works great.

First Category Id = FIRSTNONBLANK(Category[Id], 1) 

Number of Competitors = 
VAR CategoryId = FIRSTNONBLANK(Category[Id], 1) RETURN
CALCULATE(
	COUNT(Products[Apir]),
	FILTER(ALL(Products), [First Category Id] = CategoryId)
)

The above result is that I get the number of products in the category, spot on. (Maybe it could be simpler???)

Next is where I'm stuck.  I want to list a table of all the competing products.  I've tried a few things but I haven't got it right. Based on what I did above, this is how I was looking at approaching the problem.

Competitor Products = 
VAR CategoryId = FIRSTNONBLANK(Category[Id], 1) RETURN
CALCULATETABLE(
	Products,
	FILTER(ALL(Products), [First Category Id] = CategoryId)
)

What I see in the table is all the products, they're not being filtered to the category.  I know i'm doing something wrong, just trying to figure this all out.

Many thanks