Can I choose which tokens are visible on the widget?

Yes, 2FAS widgets don’t show all codes by default, so you have to select the tokens/codes for widgets to work properly.

Android – when adding the widget or after adding it, click the gear icon in the upper right corner of the widget and toggle chosen tokens.

iOS – when adding the widget or after adding it, hold it and when the window appears, tap “edit widget” and choose the tokens/codes.
Remember, if in any of these steps you cannot see the codes to choose from, although they are added in the app – you need to open the 2FAS app, and in Settings toggle on the widgets.