The reason for determining who is a "great power" is systemic, not based on individual country characteristics. India could be much stronger than russia, but if its surrounded by countries that are quite strong, it's hemmed in and not capable of dominating its region and hence not able to rival the real world powers (/ great powers).
A great (or "world") power is one which can leave its region militarily and could withstand an attack from the biggest power in the system (ie., the US).
All world powers see non-world-powers as their instruments: the EU was the US's instrument -- by bribery, threat, and protection racket it would get its own way, enrich itself, etc.
From the pov of these powers only they are soverign: hence vitnam, iraq, afganistan, cuba, etc. Hence the US engaging in a proxy war in ukraine in the first place.
India has pakistan and china to deal with, and its very unclear it can actually leave its area of the world. Hence the US doesnt have to treat it seriously. The only threats (to the US) are the powers that can withstand the US and "go on expiditions" with their militaries in regions that undermine US interests, and so on.
Here the US, mostly quite correctly, believes it can establish a detent with Russia -- but cannot with China. Russia is well-integrated into the western system, and only seeks to dominate a region the US has no interest in. The riskto it from china is far greater. It is very easy to imagine China in the western hemisphere, with a navy in a south american country -- it's nearly impossible to imagine this from India (and its highly unlikely from Russia).
India poses zero risk, nor is it clear it could ever. So regardless of what criteria you use, it will not factor into the thinking of the world powers.
The US in the 90s wanted poland (et al.) to be within its sphere of influence in the EU -- it's own instrument. It got its way. It over-reached trying to bring georgia and ukraine into the system, thinking Russia too weak to do anything about it. Well Russia isnt too weak, it has rebuilt its global status. So the US is running away and trying to reformulate a less ambitious foreign policy which its actually capable of executing