Preferably want to hear from people who actually liked the Fable series. While Fable had a linear story line, you could go off the rails a bit and even have multiple endings. Is this game kind of like that? Thanks!

This game heavily focuses on the gameplay over the actual story.
I basically spend 20h exploring before I even got to one of the main cities where the faction quests begin, the quests mostly facilitate the gameplay features, you won't be getting the standard RPG story in Outward, it's structured similarly to a MMO story.

Does this game actually end after it's all over or can you keep exploring and fighting forever?

You can keep exploring.

I love Fable 2. Outward doesn't really compare to Fable at all. There are no NPC interactions except for some basic text boxes, no relationships or marriage or kids or having sex. The clothing options seem to be smaller but all the clothes and armor have protection and heat and cold protection. You can't buy property or own a business. You can't choose between good or evil actions. You can't break in houses or rob shops. There is no "economy" simulation.

The world map has more open space, there are survival elements such as thirst, hunger, getting too cold or too hot, sleepiness, etc. You can camp out in the wild with a tent and cook food and make weapons and clothing out of available resources. The combat has that dodge and block "souls" style.

The character models have literally NO facial animations and only basic animations like walking, running, fighting.

It sounds like I'm talking negative on Outward, but I'm not. I'm just comparing it to Fable. Outward is fine for a game by a tiny indie developer. I would compare it more to the classic Gothic series, even then the original Gothic had NPC's that would react to you walking around waving your weapon around or stealing stuff from them.

Just think indie open world survival game with good combat, and minimal budget for presentation.