I recommend using:
COUNT() returns numbers of cells containing valid numbers : if none, the value will be 0, so the condition will evaluate to false and return 0 (you can put "" instead of 0 if you prefer). Otherwise, it will use the result of the AVERAGE function.
The problem with your Excel's formula is that AGGREGATE is not a Google Sheets function. While both apps belongs to the same "family" and there are a lot of common functions / features there are other that are unique to each app.
Maybe QUERY could work for you
Using AGGREGATE formula on Google Sheets - Finding the correct result based on 3 columns ...
Insert a first scorecard with Shopify n°1 as a data source.
Insert a second scorecard with Shopify n°2 as a data source
Select both > Right-click > Blend data
You create a blended data source by joining the records in one data source to the records of up to 4 other data sources. To join the data, each data source in the blend must share a set of ...
=sum(INDEX(B2:F2, 1, 2):INDEX(B2:F2, 1, 4)) to be entered in cell B2.
Since the "INDEX" function includes B2, the range will expand to include any new columns inserted to the right of B2.
"INDEX" is used to give a starting cell and an ending cell for the "SUM" function.
The starting position is the cell immediately to the right of cell B2
The ending ...