I've heard of possible spin-offs, but I don't exactly follow the show so a movie could be in the works. If zombies are your thing you might like Bloodshot with Vin Diesel. It's kind or trashy, but in a good way, and the action scenes are fantastic.
I have been watching the spin-off The Walking Dead, World Beyond. It just started, 2 episodes in. It makes little sense to me so far. I'm really not sure how it is related to the original.
AMEN! It's been a big let down for a show that had such a great premise and a lot of material to work with. My wife and I got bored with The Walking Dead at times, but we were so deeply invested that we continued to watch every season. We weren't obsessive about catching every episode, but we saw most of them. I'm not doing that again! If it doesn't improve by the fifth episode I'm out.
I'm watching both right now. I just started to binge watch Fear the Walking Dead. It's okay for now. I agree that the World Beyond isn't great yet. It's slow! The walkers "empties" are slow and dumb. I hope it gets better.