Not just "plausible". I'm talking about near exact, not just "plausible" simulation of the signals they will consume and produce, in time domain, at an arbitrary time resolution. There's no "package" for that.
The issue is that we don’t know if our neuron models are complete. Massive simulations are the easy part—computers are very, very fast and large these days.
Yann LeCun said decades ago that in spite of all the progress there won't be anything artificial that's as smart as a rat in his lifetime. In 2021 that bet is still a safe one.
We can model many billions of things at once. Take a look at the spinnaker system. Sure, we're not at the level of simulating 100 billion biologically plausible neurons yet, but we can do a few billion and the techniques are likely to scale well.