I can only filter by tags but what would make most sense for me is to filter by parent cards.
I use parent cards for projects, areas, resources - using PARA method by Tiago Forte (see attachment). So one card almost always has 2-3 parents: project, resource (topic), area. I do it because cards are hierarchical while tags aren’t manageable enough for this. I use tags for consistent metadata like #document or #in progress. Power of networked note-taking is in discovery of connections. Now it’s very limited for me in Supernotes Overall, Supernotes are super, though