This can be a little easier said than done, but if you have a large social media following, you can definitely earn money promoting a product or advertising for a company. You can even combine this with different marketing campaigns if you are an influencer and have your own blog (advertisement + affiliate income). This is how many bloggers make money! Again, it is not 100% passive but once set up correctly and then scaled, can be surprisingly lucrative.
P2P lending is a legal business recognised by RBI: P2P lending platforms are legal and the RBI has categorised them as NBFC-P2P through a notification in August 2017. In October 2017, the RBI issued regulations for P2P lending. All P2P platforms are regulated by the RBI just like banks and NBFCs. So lending through P2P platforms is a legal business.