To give you an answer to this question, we need to account for your target audience’s preferences, your competitors’ existing solutions, and, of course, your current situation: business objectives and financial capabilities.
To give you some guidance, consider choosing a web platform MVP in case you have some unique idea in mind and you need to validate it. If you want to localize one of the time-tested trading platforms, let’s say, just by launching a Robinhood-like product in your country, you can safely choose stock market app development.