These days I'm doing something similar. Using only my iOS devices, and my Chromebook, for sensitive sites. On the Chromebook, I take it a step further by using the Android version of Firefox Focus. In theory, that gives me both the inherent security of Chrome OS, and security of the OS's Android container. Almost a poor man's version of Qubes OS in a way.

I'm not sure this is the best approach, and I'm becoming less comfortable with Google and Chrome OS on general principles, but I do feel more secure with iOS and Chrome OS than I do with general purpose computing devices.