This is a practical question about kitchenware, and the answer depends on your household size and cooking habits. A 1-liter pressure cooker is actually quite small for most households' daily use.
For a single person or couple, 1 liter might work if you cook small portions and are comfortable cooking frequently. You could make dal, rice, or small vegetable dishes. However, for a family of 3-4 people, 1 liter is frankly too small.
Practically speaking, a 3-liter pressure cooker is the minimum for daily household use for a small family (2-3 people). A 5-liter cooker is better for families of 4-5 people. If you cook for guests or batch cook, consider a 7-8 liter cooker.
Usage also matters. If you're using the pressure cooker just for specific dishes occasionally, 1 liter might work. But for daily cooking where you're making rice, dal, and curries regularly, it's too small.
My recommendation: Unless you live alone and cook in very small portions, get at least a 3-liter cooker. The 1-liter size is quite limiting for daily household use.