One of the full size iPads with the capability to take a SIM card and then a data plan, maybe Lebara, good deals, they use the vodaphone network.
Then you can trade from anywhere there is a signal, hopefully on 5G too, so long as your broker has an app, or is accessible via a web based platform.
If you want to use a laptop then maybe investigate mifi devices, rather than rely on public WiFi, up to you.