Not only did they drop linux support, they dropped support for paying customers via Amazon. I had been paying for HBO via Amazon Prime Channels to watch on my FireTV and also logging into HBO Now on my Nvidia Shield for 2+ years now. HBO just recently shut down HBO Now though and "upgraded" it to HBO Max, but does not allow Amazon users to log back in.
After trying to contact HBO Max and HBO Now they both refused to acknowledge the issue so I just canceled my subscription. The only option I would have to watch on both devices would be to sign back up to HBO Max directly instead of HBO via amazon, but I'm good. They lost me as their customer due to their squabble with Amazon.