Unfortunately it is not possible to use the “Cell” from the Standard Library (Cells) in the Fixed Grid/Canvas Layout. Just like in the Masonry section of the “normal” layout. What is the reason for this, and is there any way to use it anyway?
I’m no expert but the difference between a cell and a card is just that. You use cards in the fixed layout and cells elsewhere.
As for a reason, I think that cells are a fixed size whereas cards can resize based on the availalble screen realestate.