I'm also not sure this is a useful conception of "ultimate truth".

Obviously we'd like to know the implementation details of our reality in as much depth as possible.

But Mt. Rushmore, a photograph of Mt.Rushmore, a realist painting of Mt. Rushmore, an impressionistic painting of Mt. Rushmore, an anime-style cartoon of Mt. Rushmore, Mt. Rushmore built in Minecraft, Mt. Rushmore built out of legos etc. etc. are all in some "ultimate" sense Mt. Rushmore. In that sense it doesn't matter dreadfully much whether the implementation details happen to be oil paint on canvas or little stackable boxes of ABS plastic with pegs. They're just different substrates for the same pattern.

So if I am sitting in a chair, whether the electrostatic repulsion that keeps me from falling through it is implemented with virtual particles or something else is interesting ontologically, but in some sense actually not that much more profound than if you added 47 + 265 by counting, by long addition, or by noting that 47 = 50 - 3, and 26+5 = 31 so 315 - 3, so 312.

You still got to 312, and I'm still sitting in a chair made of atoms. (I am also made of atoms.) Objectively.