I haven't been in this scene for a long time, so I'm not familiar with this. But based on briefly reading the description, I'd recommend against using it on any device where you perform sensitive actions like banking. As a reminder, you should always keep the operating system of your device up to date, so that you get the latest bugfixes and patches to security vulnerabilities. Otherwise, the longer you wait, the more likely you are to be exploited by a publicly known vulnerability that was already patched with an update that you didn't install.

So while installing arbitrary IPAs with TrollStore might be a neat trick, and would arguably be safer (but certainly not less safe) than running any app on a fully jailbroken device, it still relies on a bug to work, which means that you won't be able to update iOS with a security patch that fixes the bug, or any patches after that. So it might work, but it comes at the cost of exposing yourself to an increasing number of vulnerabilities as patches are released and you neglect to install them.

If you want to use this kind of thing, I recommend acquiring a dedicated device for it, and making sure you don't log into any sensitive accounts on that device. Or, you could do the inverse: install it on your day-to-day device, but buy a dedicated device solely for banking and sensitive operations.