I don't see the reason to trade small amounts, it is not profitable at all. Start with $ 100 at least, besides, there is a limit on the amount that can be deposited on the exchange. Also you can increase your trading sophistication by demo-trading.
Many people want crazy challenges at work, and that's why they want to trade with small budgets, but sometimes the amount of capital they want to use for the real challenge is too small, I can't know how they can trade for so small amounts. The minimum amount of capital should be as you say, $100 or more if we can, it is a necessary condition for exchange to allow us to trade, and I do not encourage trading demo when trading demo will not help us to improve, only real money battles will do that