Thank you all for your replies. The replies are highly helpful for me.
OP, how frequent do you want to perform trading? If it's just once or twice, LN doesn't bring much benefit since you need to pay on-chain TX fee when opening and closing LN channel.
I use the lightning network that has their own channel which means I do not need to open a channel. I know it is custodial but what you said is one of the reasons that I do not open a channel for myself.
But recently I have come to think of it that if I open a channel on wallet like Electrum and I funded it, I mean with two Electrum wallet to open the channel, I think I should be able to send money to another person that did not open a channel with me. If it is like that, I do receive money frequently on my centralized exchanges accounts through on-chain and I can send bitcoin to my lightning wallet or the decentralized exchange (in exchange for fiat) using the centralized exchange lightning network. Or with that I can also send bitcoin from my lightning wallet to decentralized exchange in exchange for fiat.
I am planing this because the government in my country is getting harsh against cryptocurrencies recently. They have taken down Binance P2P already for my local currency pair and I am hearing the rumor that they may they may go after other exchanges soon which will make us to depend on decentralized exchanges but I can not cope with the transaction fee.