The vacuum energy, in flat spacetime, vanishes: That's what vacuum means, the absence of excitations.

Any field configuration of known forms of matter has a non-zero energy density, which means a non-zero number of particles per unit volume, since the excitations of any of these field are particles. For the electromagnetic field these are photons, for the electron field they are electrons and so on.

Stam Nicolis Surface of water also remains dormant and calm until it is disturbed.

And its excitations are water waves, which are coherent superpositions of its molecules, which, in turn, are bound states of atoms: The superposition of the complicated motion of the atoms and molecules is much simpler to describe, that's why the description in terms of waves is more useful. When it is possible to resolve the motion of the molecules, the wave decription is less useful-but they are equivalent.

However the statement that the magnetic field around a magnet stems not from the magnet but from the vacuum is false: The magnetic field's source is the magnet. Were the magnet not somewhere, there wouldn't be a magnetic field anywhere.

This

“Are all particles essentially coherent excitations of the vacuum energy?”

- is a transcendent question since in mainstream philosophy and sciences including physics, all fundamental phenomena/notions, first of all in this case “Matter”– and so everything in Matter, i.e. “particles”, “fundamental Nature forces” – and so “fields”, etc., “Consciousness”, “Space”, “Time”, “Energy”, “Information”, are fundamentally completely transcendent/uncertain/irrational - while really they all can be scientifically defined only together.

So in every case when the mainstream addresses to any really fundamental problem, the result completely inevitably is transcendent/mystic something; that in italic, is a typical example.

The fundamental phenomena/notions above can be, and are, really scientifically defined only in framework of the Shevchenko-Tokarevsky’s really philosophical 2007 “The Information as Absolute” conception, recent version of the basic paper see

https://www.researchgate.net/publication/363645560_The_Information_as_Absolute_-_2022_ed

- where it is rigorously proven that there exist nothing else than some informational patterns/systems of the patterns that are elements of the absolutely fundamental and absolutely infinite “Information” Set. The Set exists absolutely objectively, because of it fundamentally – logically - cannot be non-existent and so exists absolutely eternally, having no Beginning and no End;

- while the utmost general scientifically rigorous definition of the so absolutely fundamental phenomenon/notion “Information” is:

“Information is something that is constructed in accordance with the set/system of absolutely fundamental Rules, Possibilities, Quantities, etc. – the set/system “Logos” in the conception”

Including “Matter” - and, of course, everything in Matter, including particles and fields, are informational patterns/systems [IPS] , while “Space”, “Time”,, “Energy”, “Logical Rules”, etc. . are “Logos” elements.

The Logos element “Energy” is actualized absolutely obligatorily in every IPS as:

“to change state of any IPS, including to create any IPS, it is necessary to spend some portion of [really mysterious, including in the conception], phenomenon “energy”.

More concretely how the Logos elements above are concretely actualized in concrete the Set’s element “Matter” it is clarified in the Shevchenko-Tokarevsky’s Planck scale informational physical model, which is based on the conception, two main papers are https://www.researchgate.net/publication/391209088_The_Informational_Conception_and_Basic_Physics, and

https://www.researchgate.net/publication/383127718_The_Informational_Physical_Model_and_Fundamental_Problems_in_Physics

Including the whole model contains initial Planck scale models of “particles” and “fields” - that are specific disturbances in the Matter’s ultimate base - (at least) [4+4+1]4D dense lattice of primary elementary logical structures – (at least) [4+4+1]4D binary reversible fundamental logical elements [FLE], which is placed in the corresponding Matter’s fundamentally absolute, fundamentally flat, fundamentally continuous, and fundamentally “Cartesian”, (at l east) [4+4+1]4D spacetime with metrics (at least) (cτ,X,Y,Z, g,w,e,s,ct), FLE “size” and “FLE binary flip time” are Planck length, lP, and Planck time, tP.

Particles are specific cyclic disturbances/cyclic algorithms that run on FLE hardware that are created if a lattice FLE is impacted with transmission to it some at least 4D (cτ,X,Y,Z,ct), momentum, P , and energy portion, E.

At that it is possible, in principle, to say “excitations in the lattice” instead “disturbances”, though the term “excitation” in this case is rather vague; however “excitations of energy” is fundamentally wrong - again , there can be only excitations of states mostly systems of coupled by a Force particles and the Forces fields, when the states’ energies change; when “excitations of the vacuum energy” furthermore wrong/[+transcendent, see above].

Cheers