It's been over a decade since my cosmology class, so forgive any errors, but isn't there a constant that describes the curvature of the universe [1], which so far has been calculated as "flat"? That's not to say we'll ever truly know, since you need infinite precision to rule out hyperbolic or spherical geometry, but in a flat universe, how can you have toroidal geometry?
Per [2]:
> The actual value for critical density value is measured as ρcritical = 9.47×10−27 kg m−3. From these values, within experimental error, the universe seems to be flat.
[1] - https://en.m.wikipedia.org/wiki/Friedmann_equations#Density_...