`git checkout $branch`, but handles files that are assumed not to have changed.

cgo.nu

# use cgo.nu

export def main [branch: string] {
  let result = (do { git checkout $branch } | complete)
  let stderr = $result.stderr

  if $result.exit_code == 1 or ($stderr | str contains 'Your local changes to the following files would be overwritten by checkout') {
    let files_to_save = ($stderr | rg '^\s+(.+)$' -r '$1' | lines)
    let tmp_dir = (mktemp -d)

    touch $"($tmp_dir)/EMPTY"

    for f in $files_to_save {
      let f_tmp_path = ($tmp_dir | path join $f)
      mkdir ($f_tmp_path | path dirname)
      cp $f $f_tmp_path
      git checkout --ignore-skip-worktree-bits $f
    }

    git checkout $branch

    for f in $files_to_save {
      git merge-file $f $"($tmp_dir)/EMPTY" ($tmp_dir | path join $f)
    }

    rm -rf $tmp_dir
  } else {
    echo $stderr
  }
}