Ask HN: What's the best privacy friendly Android email app?

I'm moving everything off Google as best as I can at the moment, switching to Fastmail, etc.

My biggest issue at the moment is finding a trustworthy app to use for my email (personal and work).

I've used Gmail forever and have come to love the interface and such on my phone.

I've tried K-9 and while it gets the job done it is extremely clunky and it really makes sorting through emails a chore in my opinion.

There are a few other options that are paid via the Google Play Store like Nine and CloudMail and such, but I don't know how legit these are and I don't want to be handing my emails + logins to some random third party.

Is there a better option than K9?

I'd love to use the Fastmail app as it is great, but I NEED offline support as I travel a lot and am out of service quite often.

Thanks!