Tom just a quick note to say that I really think you’re onto something here. You have articulated a central problem which is hard to tackle with our current stack. (Also closely related to the L2 satellite data processing challenge identified by @cgentemann in Get Involved in Pangeo: Entry Points for New Contributors - #7 by cgentemann). Your solution elegantly leverages the existing tools (Pandas, Xarray, and STAC) in a really neat way. I would definitely keep pursuing this.
I think the next step would be to define a workflow–say to create a cloud-free mosaic of a region or something like that–and see how this approach maps. I would talk to Chelle, @RichardScottOZ, and others working with L2 data to identify some candidate workflows.