Imagine, I have put stop loss order for one crypto at $0.301, is it possible that if no one put a buy order at this price, my order will not be filled?
Yes, it will not be filled. That is why you need to trade cryptocurrencies that have high marketcap. Also on the exchange you trade, you need to make sure the coin has high trading volume. Cryptocurrencies like bitcoin will certainly be filled immediately because of that. But, shitcoins can never be filled because the trading volume is low, but if people sell at such price of your stop loss, your trade will be one of the first to be filled.
Although the event is very unlikely to happen but, technically it's possible that no buyer put an order at $0.301
It can happen for shitcoins, and you will be frustrated.
What will happen to my order?
In this case, you will have no option than to use the market order, but market order can be so risky. If the coin is at $0.301, what could make the stop loss it to fill will make the market order price to be very low if compared to the limit order price. Some people will still want to buy and might have even place the order to buy at lower price but not yet filled. So, using the market order will match the price people want to buy which is very low to the price people want to sell. Like the market price for the price of limit order proce $0.301can be $0.1 or even less. Then, if you are able to loss that much, then you can sell.