trust wallet is not an opensource wallet. It doesn't matter whether it's an open source wallet or not but when you are storing a lot of money in your wallet and you must try to make your the key to open your wallet will be in the safe place. I mean your wallet will be secure when you are the only one who know how to open your wallet.
I have used electrum, exodus and various wallet to store small - big amounts of crypto.
As long as you can keep your key in the safe place and your money will be safe.
It doesn't matter whether it's an open source wallet or not, Yes I agree with this, the most important of the crypto wallet is the private key. I also use many kinds of wallet but I never do research first that the wallet open source or not because is not important for me, I just keep in my mind that the private key is kept in a safe place. And until now all safe