Here are some ideas I had:
Bangabhumi: This is IOTL movement for Hindus in Bangladesh, and in 2003 some declared independence for the "Hindu Republic of Bangabhumi". If you manage to make it independent in your TL it might become the world's first Hindu Republic.
Khalistan: A movement for a Sikh republic which claims all of Indian Punjab as their own. It was actually a thing in the 1980s and 1990s before dying down. If you manage to become independent in your TL it will become a Sikh Republic, I think.
Any other ideas?
Bangabhumi: This is IOTL movement for Hindus in Bangladesh, and in 2003 some declared independence for the "Hindu Republic of Bangabhumi". If you manage to make it independent in your TL it might become the world's first Hindu Republic.
Khalistan: A movement for a Sikh republic which claims all of Indian Punjab as their own. It was actually a thing in the 1980s and 1990s before dying down. If you manage to become independent in your TL it will become a Sikh Republic, I think.
Any other ideas?