In the UK, banking apps are optional, I can use website in browser.
With GrapheneOS, you can install Play apps sandboxed and with dummied google apps and control how much of the file system they can see etc.
I would assume outlook has a web client. Not sure what InTune is so cannot comment.
Ewww. No way would I install that on my phone. It would be on a work specific phone that I don't give a crap about :). I doubt you can get much privacy on corporate mobiles with that shite :).