The Trust Wallet Core library is open source but the app itself is closed source. Many of the popular multi-coin wallets aren’t fully open source either. If you are using altcoins, Trust Wallet isn’t any better or worse than Metamask.
A hot wallet is only fine for small amounts. Hardware wallets are always the preferable option because it is much harder to lose funds due to having a compromised device.
It's popular doesn't make it the best, trust wallet started well but since the takeover by Binance everything has changed for the wallet. It isn't a recommended wallet because you don't have control when using it. Don't be surprised if your coins gets frozen due to some investigation that you have nothing to do with. Trust wallet is just like using Binance exchange wallet for your savings. For small transactions you can use them but not as your main platform of storing your crypto. We have many better choices either hardware or software that are also user friendly. Electrum that you think isn't user friendly actually is, when you get more familiar with it
Trust Wallet is non-custodial, Binance can’t freeze your coins. You can import your seedphrase into another wallet if you are unable to use it for any reason.