Does jostling to compel people to kiss the Black Stone in the Grand Mosque in Makkah harm others, and is it considered part of the hardship of Hajj or Umrah, as some justify it?

The Black Stone, not the Blessed Stone, and kissing it is a Sunnah, not a condition or an obligation in the circumambulation (Tawaf). So, whoever can kiss it without harming anyone, let him do so. Otherwise, it suffices to point to it with the hand. It is not permissible to harm people by pushing and shoving, and it is obligatory to respect the sanctity of the place and the people.