Having traditional trading platforms accessible through Telegram mini apps will not only make these platforms more accessible and save space for apps download but will provide opportunities for newbies and airdrop hunters to receive airdrops cos these trading mini apps come with reward to incentivize users.
I could only think a mini version feature for trading might be possible. Knowing that exchanges have its own api to start with for different features including safety and security of their funds mainly hot wallet. If they will apply it on third party apps it could lead to potential risks ssince you will need to trust telegram with those information.
Anyways, you wouldn't put lots of money both on CEXes and a potential mini-app for trades, if you know what's up and the risks attached to it - however, I do think it would be really great to combine both into one

Imagine combining the TON eco (which I hope to be better as time goes on) with the created trading app.. That would be great indeed.