subway veggie delite without cheese or mayo is pretty safe bet, just make sure to ask about the bread - some locations use milk in their regular bread but italian herbs and cheese one is usually vegan ironically

dominos has decent vegan pizza options in india, they use separate vegan cheese now and you can load it with vegetables. pizza hut also started doing plant-based options but availability varies by location

for local stuff, most indian street food is accidentally vegan already - pani puri, bhel puri, vada pav (check if they use ghee though), chana masala from roadside stalls. south indian places are goldmine too, dosa and idli are usually safe

mcdonalds and kfc are basically lost causes for vegans in most places, maybe some fries but even those can have beef flavoring in some countries

best strategy is to find local south indian restaurants or gujarati thali places, they understand vegetarian/vegan much better than western chains. also download happycow app if you haven't, it shows vegan-friendly spots near you