Did you look at the file? Yes, comparatively using a non-declarative approach would render much simpler code. Perhaps the author is not writing SwiftUI proficiently? Having used SwiftUI myself I would argue that this is not the case.
It reminds me of why I am not a big fan of Flutter either. Not a fan of the deep nesting which both SwiftUI and Flutter needs to do for even moderately complex UIs.
This is a fun project so whatever code goes, but this could easily be broken into many small chunks. There’s even a context my button to pull subsections out into smaller strict automatically.