Read more about it here: https://www.julienphalip.com/blog/git-hard-rebase/

git-hard-rebase.sh

# Takes two parameters: target branch and commit message.
# Does a hard reset on the target branch then adds a single commit with the diff
# between the two branches. Sort of simulates a rebase but without having to
# resolve potential conflicts in intermediary commits.
function git-hard-rebase() {
  # Parameter validation
  if [ "$#" -ne 2 ]; then
    echo "Usage: git-hard-rebase <branch-to-rebase-on> <commit-message>"
    return 1
  fi

  # Store the original directory and move to repo root
  original_dir=$(pwd)
  repo_root=$(git rev-parse --show-toplevel)
  if [ $? -ne 0 ]; then
    echo "Error: Not in a git repository."
    return 1
  fi
  cd "${repo_root}" || return 1

  # Validate branch exists
  target_branch="$1"
  if ! git rev-parse --quiet --verify "${target_branch}" > /dev/null; then
    echo "Branch name ${target_branch} does not exist."
    cd "${original_dir}" || return 1
    return 1
  fi

  # Validate commit message
  message="$2"
  if [ -z "${message}" ]; then
    echo "Message is empty"
    cd "${original_dir}" || return 1
    return 1
  fi

  # Create diff file
  current_branch=$(git branch --show-current)
  file_diff=$(mktemp "/tmp/${current_branch}.${target_branch}.XXXXXX")
  echo "Diff file: ${file_diff}"
  git diff "${target_branch}" > "${file_diff}"

  # Validate diff is not empty
  if [ ! -s "${file_diff}" ]; then
    echo "Warning: Diff file is empty. No changes to apply."
    rm "${file_diff}"
    cd "${original_dir}" || return 1
    return 1
  fi

  # Create backup and reset to target
  backup_branch="backup/${current_branch}-$(date '+%Y_%m_%d-%H_%M_%S')"
  git branch "${backup_branch}"
  git reset --hard "${target_branch}"

  # Apply changes and commit
  if ! git apply --verbose "${file_diff}"; then
    echo "Error: Failed to apply the patch cleanly."
    echo "You may need to resolve conflicts manually."
    echo "The diff file is located at: ${file_diff}"
    cd "${original_dir}" || return 1
    return 1
  fi

  # Verify changes were applied
  if git diff --quiet; then
    echo "Warning: No changes were applied by the patch."
    rm "${file_diff}"
    cd "${original_dir}" || return 1
    return 1
  else
    git add -A
    git commit -m "${message}"
    echo "Changes have been committed."
  fi

  # Cleanup
  rm "${file_diff}"
  echo "Hard rebase completed successfully."
  cd "${original_dir}" || return 1
}