Use Row/Index number as Variable in Power Query

I'm working to learn how to expand Binary Data out in Power Query, and trying to figure how to reference the row/index number in trying to make a function.

I have something like this in power query:

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And I can't figure how to convert the {0} to be a variable. It should be referencing either the row number or the index column. I created an index column starting at 0, thinking I could then reference that.

But this doesn't work
Content = #"Added Index"{[Index]}[Content],

nor does this
Content = #"Added Index"[Index][Content],

Any ideas? Is this a syntax issue or something else?

I'm probably not thinking this out logically in my head, or maybe over thinking the entire process.

The built in expansion of the data (that double arrow) errors out trying to combine. I think that is because I'm attempting to unzip a zip file that has 50 excel files in it (not csv), and then also select and transform only 1 worksheet from each of those 50 files. I likely need to build and setup a function or two, just haven't figured it out yet.

Attempting to use the build in function returns an error of "We didn't recognize the format of your first file ().

I have a similar question open on the Power BI forums, and don't want to go cross/double posting. But I'll keep thinking more on it. It's probably much easier than I'm making it out to be.