You need to learn yourself some molecular geometry. An octahedral molecule forms a perfect right angle due to its bonds. Sulfur Hexafloride (SF6) is one of those molecules. So yes, nature makes perfect right angles.

A quare is defined as having four right angles. By your definition of right angle, you've never drawn a square in your life.

Stop being a pedant and admit that you learned something today.

Bruh that's not how any of this works.

First off, if there's always variance, then logically by random chance sometimes you must measure exactly 90°.

Second of all, how many decimal points are you measuring too? 1? 2? 10^-23? The likelihood of measuring exactly 90° definitely goes down the more places you measure to, but A: precision is only useful up to a certain point, and B: it is never 0%.

Sure when you set the goal post that far away you're right but by doing that you've made your argument so pedantic that it's just not worth arguing against. In practice at some point the variance is so insignificant and we can just say it's a right angle. If you want to maintain the position that it's not a perfect right angle by all means you're welcome to do that. I'd say, that piece of bismuth is close enough.