Buying for a father-in-law is a different problem from buying for your own dad. You have less information and less licence to be wrong. The gift has to be clearly considered, clearly not cheap, and clearly not presumptuous about his habits, hobbies or health.
That's why the ₹1,000–₹3,000 band suits this relationship almost perfectly. It sits above the token range and below the point where a gift starts making a statement about the family's finances.
Of the categories here, a watch is the lowest-risk. The Casio Enticer needs no setup, no app and no charger, and a man who already wears a watch has already told you he'd wear another one. Luggage is the second-safest: useful, impersonal in the best way, and almost everyone is quietly travelling with a bag that has a broken wheel.
The four smartwatches need a caveat. They are a good gift only if you know he already uses one or has said he wants one. If he doesn't, a smartwatch is a small daily obligation — charge it, pair it, dismiss its notifications — dressed up as a present.
The air purifier is the outlier worth taking seriously if your in-laws live somewhere with a winter AQI problem. Just know that 305 sq ft is a coverage claim on the listing, not a measured clean-air delivery rate.