Sat Sri akal ji 🙏🙏 All the Sikh gurus are of equal importance to Sikhs…and I know we should not believe in photos and should make our minds as temple.But why most people keep only guru nanak dev ji’s photo at home and not other gurus? Is there any specific reason?

None of the photograph of any Sikh Guru Sahib is real. A Sikh is not supposed to worship any photograph or sculpture.
Sikhi does not accept the worship of photographs. Those who do not believe in one God, only go for multiple Gods.
ਬੁਤ ਪੂਜਿ ਪੂਜਿ ਹਿੰਦੂ ਮੂਏ ਤੁਰਕ ਮੂਏ ਸਿਰੁ ਨਾਈ
ਓਇ ਲੇ ਜਾਰੇ ਓਇ ਲੇ ਗਾਡੇ ਤੇਰੀ ਗਤਿ ਦੁਹੂ ਨ ਪਾਈ ॥੧॥ – 654
Photographs are manmade. How can these be God? Akal Purkh is everlasting and can never be destroyed.
The type of Photographs being propagated also depends, as which one can sell more. This depends upon the public desire and intentions of the propagating agency.
However, there is no Dev with the name of any of the Guru Sahibs.
Sikhism believes in getting enlightenment with the help of Shabad Guru, so that we can have a happy and contented life.
The present situation of most of the people is that they know everything, except what Guru Granth Sahib teaches.
ਗੁਰ ਬਿਨੁ ਘੋਰੁ ਅੰਧਾਰੁ ਗੁਰੂ ਬਿਨੁ ਸਮਝ ਨ ਆਵੈ ॥ – 1399
Gurmat teaches to understand and follow the Shabad Guru. But people think that if they worship the photograph that will solve their purpose.
Hence, we have to first understand and educate ourselves and then others about the Gurbani.
We should never forward any photograph otherwise we will become the culprit to increase its TRP.
Humble reply with written content only, not to forward such messages.
Request your friends also to write against such photographs.
Always create the habit of self learning.
Groups of friends can be made to discuss Gurbani written in Guru Granth Sahib.
We should forward only 100% correct messages, after verifying them with the help of Guru Granth Sahib.
Thanks