Warframe might fit what you're looking for.

It has an overarching story and story missions, it's combat oriented, it has one of the least-predatory F2P models I can think of, and it has both open world zones and "interior" missions.

Best of all, it runs on potatoes. Might be worth looking into.

Another option is maybe Monster Hunter Rise, but I've only played a demo, and you have to consider Capcom's aggressive anti-cheat back porting.

Last one you might not have considered is Halo Infinite. I played the entire campaign with a Ryzen 5600G on medium settings and got ≈45-55fps. It's very well optimized and should run fine on weaker hardware.