I’ve tried Kodi but I spent more time skulking around trying to find stuff that works than actually watching. I got shot of it after a week or two.
It's the same problem with any software of this type (for viewing *cough* live sport), they're only as good as the "addons". And they're basically just providers of links of feeds from elsewhere. They need to be constantly updated. Kodi is one of the top addons for the firestick, from my limited investigation. I don't know how the firestick handles these things but it does seem to be current with the feeds.
I pay a small annual fee for the Whirlwind program, it does on times buffer, but on the whole it is well worth the modest fee for all the extra channels from around the world, especially sports and movies....