The reason why only the Buddha statue has no bodhisattva is because it is the imprint of the Buddha's heart and is exclusive to the Buddha.
This symbol has nothing to do with the Nazi swastika. The Nazi symbol is the shape of the cross sign used by the Nazi party formed by the overlapping of the German letter "S", which is opposite to the direction of Buddhism.
The swastika used by the Nazi Party is one of the 32 adult Buddha statues. According to Long Agama, it is the sixteenth kind of adult image, which is located on the Buddha's chest. Qianzi said in the sixth volume of Buddhist scriptures in Great Saxony that it was the eightieth kind of good image of Buddha Sakyamuni, which was located on his chest. It is said in the Ten Classics and Twelve Volumes that before Sakyamuni became a Buddha, there was a solemn image of King Kong in his heart. This is commonly known as "merit in the chest." However, in the third volume of Fang Guang's Solemn Sutra, it is said that the Buddha's hair also has 50,000 words.
In Volume 29 of Miscellanies of Pinaye, it is said that there are also ten thousand words on the Buddha's waist. "Wan" is just a symbol, not a word. It means extremely auspicious, called auspicious sea clouds, also known as auspicious happiness. Therefore, in the 381st volume of Mahayana Sutra, it is said that the Buddha's hands, feet and chest are blessed with blessings to show the merits of the Buddha.
Reference-Baidu Encyclopedia