I personally use Huawei 8372 dongle with a Jio SIM
it works fine and is controlled by an app or web interface.. It works only on wifi output and gives decent performance overall. It supports SMS also..
Check if you've the airtel dongle offer plan that is 499 a month (1GB 4G per day and 5GB bonus overall for one bill cycle - effectively 35GB). If not, i'd suggest buying an unlocked 4G dongle and buy an airtel prepaid sim and take the 84 day wala plan that gives you 1GB a day for 84 days..
But before choosing any of them, make sure the network is reliable.. and choose the one which gives decent coverage.