The UK were in India for a long time. How does that work with the magical world? I think that the Ministry is not much different from the Muggle UK government. What if they never left India. It would e really interesting to explore the fight for freedom in the magical world. There's a lot to explore here, and it can be done with an OC in Harry's year too. You can also throw in the Irish Repulican Army, which Seamus could have ties to. You have in general two more factions then - colonialists and liberalists. These can intersect with death eaters and non death eaters too, so you have 4 different factions. It'd be interesting to see a mcGonagal that's not a death eater but also is a colonist. And also a Yaxley that is a death eater but is also a liberalist. Loyalties will be up in the air and strategy is more important than ever.
Ancient India was full of various kingdoms and a rich mythology - there's a lot to explore there. A lot of new spells can come from there. The Indian magical world should look like scarred kingdoms imo. Hinduism js polytheistic. Imagine that Indian wizards can actually turn into these gods because of some special trait. Like some special form of being an animagus. Then, the Ministry feared this so they stayed in India when the UK Muggle gov left. Then you could even do something like an Attack on Titan setting. You can also have characters from different colonies as well.
Just as an example story of where to go with this, consider a young Muggleborn Indian boy goes to Hogwarts. He has to wear a special band on his arm that the white students don't have to. He always has to wear that special band all the time - een when he's asleep. Unbeknownst to him and the two other Indian kids in the school (the Patils), Albus Dumbledore fought hard for them to be let into Hogwarts. Magical Indians are usually just pushed into Knockturn Alley for backwater jobs. The first year ensues with bullying and the like, making it hard for the child to make it through. He does so nonetheless. But that summer, the child goes to visit his relatives in India. He doesn't know it, but the ministry officials in India are waiting for his arrival. Captured, the child is separated from his family and is forced to fight for his survival and escape.
At the beginning of fifth year, he returns on a ship with his face now scarred - alone. He buys a pub in the middle of knockturn alley after retrieving a few life insurance policies and hires Indians only, also setting up his own gang - the Talvars. With that the boy returns to Hogwarts, all the while running his gang. He quickly recruits and takes over Knocturn alley. But the IRA comes around the corner and so does the Ministry. With death eaters getting more and more active too, chaos ensues.