For indie games, there is no a specific market. Any theme, any styles, any details are available. Some need realistic but very low-poly count, some others need cartoons with details and some « AAA like » need detailed and realistic models. I know just that LODs, rigging (when it necessary) and PBR textures are very important to offer a minimum to the indie game market.
Also, it is very important to play (and analysis of course, not only play ;) ) indie games (many different types) to see what they do and try to find what they need.
The game design and the level design have an important place in the choice of the type of 3D models you can make. But you can also make models to embellish the environment in a game and never serve the gameplay, just a contemplative assets.
So, just to say there are no rules and no secret ingredient, just do the best quality and the most efficient model to hope to sell it to an indie studio. Look at my WWII ration cans, I have imagined them in an historical war game and finally they are in a survival game in the Amazon forest... but no matter, I love to see it in a game that I also play !