I have been thinking about what things about a point particle do all observers agree about?

And I thought trajectories of particles must be the same for all observers, right? But, clearly it is not. Because forces and accelerations are not same for all observers. As far as I could think,

Only the overall shape of a trajectory is the same for all observers

Is this correct?

Some other things that work this way (Lorentz scalars, I think I was told) are rest mass and charge of a particle. So what are some other things that are observer-independent?