It seems you can't trade using the app from binance, and the app from coinbase only allows buying and selling from an account for limited crypto currencies.
What do you mean you cannot trade in Binance using their app? I just recently making a trade there, perhaps you downloaded the wrong file, that could be put danger on your account.
You can download it on Playstore for android and Appstore if you're using IOS or you could just visit their website and check it out there.
Can anyone recommend a good safe and reliable altcoin trading app from a reputable brand (i.e. not by a random independent developer)?
I am using Binance so far and I would say that they are pretty secured, they require a lot of things that you would only know just to withdraw it. What I like in Binance is that they have the largest volume and the top leading exchanges so there's no question about their reputation.