My appreciation of quantum theory is at the Schroedinger equation level. This theory is not about particles but rather about waves with various interpretations on how the results of solving that equation might be related to particles, like the waves are probability functions that determine the locations of particles.
So the concept of a particle is introduced ad hoc under the assumption that particles exist. To my knowledge there is no theory of particles with predictive results except for classical physics which is known to be a multiple event average of quantum theory on the micro-scale.
My interpretation is that its all fields or waves. Particles are just a conceptual approximation of what happens when different types of quantum waves interact- like when quantum waves associated with the photon, or in other words electromagnetic waves, interact with quantum waves associated with electrons inside of atoms.
The terminology photon and electron is OK to use, but the thinking that they exist as point particles is a carry over from classical physics. The missing element, or theory, is an understanding of how photon quantum waves that are spread over a space quite large compared to an atom, can shrink to atommic size and change the state of electron quantum waves.
Presumably the interaction time of these two types of quantum waves is on the scale of the Planck time, so perhaps quantum gravity will result in such an understanding. But a mistaken paradigm, that particles exist like strings, (membranes are closer to the truth in my opinion), may hold back progress on that theory. I suggest that physicists change the word particle to wave in all their writings. So instead of discovering new particles in wave accelerators, they are really discovering new types of quantum waves.
There are limiting environments where the particle approximation is a good. An example is the flow of electron waves in a conductor. The waves interact so often with the medium they are in, that after each interaction, the electron waves have not had a chance to spread out very much before the next interaction. In such cases the waves are so highly confined that it is appropriate to refer to them as particles, but they really are just highly localized packets of waves. Super conductors are a different story. It is conceptually easy to understand how waves can pass through a medium without interacting with it.
I would be very interested if you know of any quantum theory that directly derives the properties of a particle rather than via interpretation.