Even the Linux nerds who customize everything about their computer are probably still using the QWERTY keyboard layout. I’ve seen a lot or “arch btw” but never seen “dvorak btw”.
I’m an Arch user and I did try Dvorak for a few weeks. I eventually gave up because it was a huge hassle switching back and forth, remapping game controls, remapping code editor key combos, and so many other remaps. It just wasn’t worth the effort.