Rigid Fork with ~510 ATC?

My 2017 Nimble 9 geometry is measured with a 551mm ATC 140mm Pike

https://canfieldbikes.com/pages/2017-canfield-nimble-9-boost

When i use a rigid fork calculator, that tells me if i want a rigid fork to replace the 140mm fork after sag i need something in the realm of 516mm ATC. i figure better to go lower at 510 than higher at 520.

Does anyone make a steel or carbon fork in that range? I found the RSD one, but looking for more options for comparison. i'd prefer it not be ridiculously expensive, but i'm toying with the idea of a rigid setup for bikepacking simplicity.