The Nokia 6 was announced for the Indian market way back in early June, but but Amazon started accepting registrations in mid-July for an August 23 flash sale. Things have been going slowly, but the interest is there Amazon just marked 1 million registrations.
It has exclusivity in the country and has put up an INR 15,000 price tag. Note that registrations are not really pre-orders, though its not clear if HMD has 1 million units to sell anyway (flash sale doesnt sound like they have units to spare).
The Nokia 3 has been available since June through offline channels (though its now on Amazon as well). The Nokia 5 also started off with brick-and-mortar sales and moved online later (seems sold out now, however).