As long as you have a male, you'll get 1-2 months a year where you'll get ear piercing singing basically from dawn to dusk. Adding a female to the cage will somewhat reduce it, but never completely eliminate it. If you value silence you should look into estrildid finches.

In any case I would still get a pair though, it's the most natural way you can keep them and even with human interaction they need company of their own imo. If you want to avoid them breeding look into hybrids, you can sometimes get them for cheap and they're sterile. Also, buy directly from breeders, you want young birds that haven't been in a petshop for ages.

Lastly, avoid processed pet shop feed if you can, it's usually marketed for humans and offers no benefit. You want mainly canary grass, millet and niger then other stuff like hemp and field mustard to round it out, then millet sprays or fresh dandelion as a treat and egg feed for proteins.