Not an expert in the process either, but I get from here that the full application (with the PR) should be finalized by April 2, from what I understood here?
That leaves time for @kimala to skim through the list of ideas and propose a first PR.
If @kimala and the rest of mentors are ok, I would propose to finalize having some of the different sparse kinds as DTs integrated in stdlib, even if not with all the methods.
That way we can then build on top APIs that have a similar signature for dense matrices following your work @FedericoPerini that take as input a DT for the given sparse type. Any thoughts?