I know this doesn't answer the question but I want to offer some advice instead.
In my opinion just don't. If the company want you to have access to emails on the go then they should give you a company phone. If they don't, why are you trying to? Don't put work things on your personal phone.
Ninemail.
I don't know all the other apps listed here but I do know last I looked Nine was the only one that actually had Exchange ActiveSync support. ActiveSync is a licensed protocol so you won't find it supported in a free app, open source or not, not without some alternative monetization that compromises your privacy. Nine has no ads and doesn't run through their cloud. It also optionally isolates the security model to the app so remote wipe and other employer policies don't apply to your OS. I also didn't want the corporate address book integrated with my personal one, and it lets me keep that separate, too.
Thanks. This one looks nice and works smoothly
I second Nine. It's a great app but has its price. Comes with a free trial for I think 14 days.
Nine can do applevel or security for exchange so you don‘t have to give your company control over your phone. Bonus points if you sandbox it in work profile via Island.
Use outlook in the browser.
I second this. The Outlook PWA for mobile is actually a fairly decent example of a web app done right compared to a lot of other ones, it works in Firefox for Android, supports notifications, and can be installed to the home screen.
GitHub or play store versions of fairmail?
https://github.com/M66B/FairEmail/releases
I don't have any Microsoft account so I can't try, but fM wizard has an option to setup OAuth
Buy a $20 burner and take that to work.Tell your boss how poor you're and ask for a company phone
Well probably not poor but say you only use a cheap phone for calls and texts or something like that.
Say poor. Might get a raise too
Look into Aquamail.
Does Spark work? It is the only other mail app I've tried and it was ok. I don't know if it supports exchange though.
If you install it under the work profile in Android does it still get screen lock control?
I've only heard of it happening, and I don't want to take any risks.
Had the same issue, and had to go withe the official Outlook app :(
Fairemail by faircode.
They have a big focus on privacy, and I run a office365-account in it without any issues.
FairEmail only supports IMAP and POP3 but these protocols are disabled according to the OP. So this sadly isn't an option. Very good email app though. I can recommend it.
Privacy has become a very important issue in modern society, with companies and governments constantly abusing their power, more and more people are waking up to the importance of digital privacy.
In this community everyone is welcome to post links and discuss topics related to privacy.
much thanks to @gary_host_laptop for the logo design :)