Yep. Pretty much any measurement you make in the real world is actually going to be irrational. We just round them to the closest significant figure we have. https://www.youtube.com/watch?v=Swm8tTLWirU

I'm also interested in subatomic particles like quarks. They're usually represented as spheres. Are they really spherical?

Similarly, the gravity of a neutron star probably compresses its own mass pretty damn closely to a perfect sphere. Though I suppose its rotation might deform it?