I have a Apple TV+ subscription, but can not log on to my account on my Buzz TV device. I have tried various browsers, including chrome, firefox, and puffin.

I am not sure if the DRM components do not function correctly because the device is not considered secure, or if apple is blocking the streams due to some other issue.

It's frustrating that with a legitimate account, that I can't access the service.

Is there a browser or app that will work?

Thank you.

So your question has nothing to do with DRM components. Rather Apple blocking or not allowing decoding on the android devices. 

I am a apple TV fan since AppleTV2 days and i don't see any app creation for regular PureOS compatibility yet. 

This app would not work on any browser nor app yet because it is not been compatible with any mobile devices. they have launched the AppleTV+ with Samsung SmartTV only 8Gen and Amazon FireTV devices.