

Well, they all have standard web interfaces, and so many apps are merely wrappers for it or a rebuilt front-end. On a Linux device one would presume you’ll have a standard web browser so all you need really is a wrapper for the website and the browser engine handles all security. Is there any reason not to just go that route?
Exactly. And as I said in another comment, you can make a wrapper for it if their website is not the most mobile-friendly. Any browser can handle everything beneath the skin.