While I’m excited for what Monzo has to offer in the future, the issue for me is; If I’ve got my phone and my card/wallet in my bag, and I’ve left my bag on the train, and I’m stuck in London, how am I going to freeze my card, with my Santander, I’d get to the location I was heading and access my bank through there, a web interface is almost a “MUST” for me (Somewhat rhetorical, not looking for an answer, just putting the scenario out there)
In terms of mobile application, it may be worth looking at a PWA (Progressive web app) as I don’t give it more than 10-20 years before instead of installing applications we’ll be bookmarking a PWA to use. Perhaps “Online first” would be better than “Smartphone only”, you’re limiting your target audience by doing smartphone only, it’s one of the reasons some people I know won’t register.
Google is already on this route with their FuchsiaOS, whereby they’re limiting installed apps, and you can bookmark a website and use it the same way you would an application. Microsoft has also moved their focus towards stopping users installing things, and iOS from 10 I think allows you to use PWA’s efficiently.
On another note, you only have to develop for one platform, web. Currently you have a team of Android developers, team of iOS developers and that’s great, making sure the base is covered, however if you had one small team of PWA/Web developers, you’d have an application for Desktops, Laptops, Tablets, iOS, Android, Windows, Consoles, anything that could access the internet.
Infographic on PWAs: https://insanelab.com/wp-content/uploads/2017/01/xprogressive-web-apps-infographic-1120x1680.jpg.pagespeed.ic.4CRLJQoCDu.webp