PKM apps are trees of strings! It's fast until its not. Even if you can sync the global dataset to the device storage, the query engine needs data in process memory and still has to traverse it with device levels of compute not cloud compute, "instantly" i.e. without making the UI feel sluggish. If you feel otherwise, use Roam or Tana for a year, even in single-player mode. The entire category is bottlenecked on this scale problem. And now add team support, because you want to sell this to teams and make money, right? Designing for casual, personal-sized datasets is a viable architecture in very few apps. Google Maps is one shining counterpoint, because the content has a natural locality to it – you only need to sync content near where you are geographically!