Hi Bruno,
We haven’t fixed this issue yet, but we are considering a few options in coming months for addressing this. We were hoping for exactly the kind of input you provided: a sparse/compressed matrix format with the full dataset would be really valuable (as opposed to direct API access for subsets or separate downloads for individual cell types or subclasses).
I’ll post back here when we have a planned update on our roadmap. (The team is busy working on some exciting features for patch-seq data at the moment!)