Millets are not one grain. Five small ones turn up in Indian kitchens under a dozen names, and one may already be in your vrat dabba.
Sanwa, sama, oodalu. Barnyard millet is the small, rice-like grain many families already cook on fasting days. Familiar, not new.
Kangni, thinai or korralu. Mild in flavour and suited to rice-style dishes, khichdi, pongal and upma.
Kutki, samai, same. Small and delicate, little millet works especially well in upma, pongal and soft porridge.
Kodon or varagu. Distinctly earthy, enough that you will notice it. Best in khichdi, porridge and savoury grain bowls.
Sold whole or as flour, and hardest to find. Rarity gets marketed as superiority. Unfamiliar does not make a grain better.
Polished or unpolished changes both the fibre and the cooking time. Buy small, follow the packet instructions, then decide.