There is no way I am going to be able to pull a fiber through a 3/4" conduit that already has two direct burial Cat 6 cables in it.
Don't even try. Fiber does not address reasons for damage.
Two structures. Every wire incoming to each structure must connect low impedance to that structure's earth ground before entering. If any wire inside any incoming cable does not, then all protection is compromised.
That is single point earth ground. And not any other ground.
A Tech Note demonstrates this concept. Every wire (overhead or underground) is a potentially incoming destructive path. Protection only exists when each wire connects to earth BEFORE entering. Only then is a surge not anywhere inside.
Every good protector has a dedicated wire to make that low impedance (ie less than 10 foot) connection to single point earth ground. Since earthing electrodes (and not any protector) define all protection. Protectors are only connecting devices to what does all protection. From all surges including direct lightning strikes.
If that properly earthed solution does not exist, then a surge in one structure is also a direct (and destructive) connection to electronics in that other structure.
Nothing new here. As done over 100 years ago in facilities that could not have damage.
Your telco CO suffers about 100 surges with every thunderstorm. How often is your town without phones for four day while they replace that $million computer? Never? Because this is the solution also found in every telco CO all over the world - when damage cannot happen.
They don't waste tens or 100 times more money on magic protectors that will somehow 'block' what three miles of sky cannot. They do not waste money on magic protectors that are only rated to 'absorb' thousand joules. Instead, they earth effective protectors. That means a connection, to what harmlessly 'absorbs' *hundreds of thousand of joules* (earth ground electrodes), is low impedance (ie has no sharp bends or splices).
No protector does protection. Not one. Best protector is only a connecting device to what does all protection - single point earth ground. Most attention focuses there when best protection is desired. A protector is only as effective as its earth ground.
That 3/4" conduit has multiple Cat 6 wires? All must have same ethernet protection at both ends. Located to make a low impedance (ie less than 10 foot) connection to each structure's earth ground. Otherwise all protection is compromised.
Same applies to every incoming AC electric wire.
Expensive fiber would accomplish almost nothing.
Best protection at each appliance is already inside each appliance. Includes galvanic isolation in each ethernet port. Good for maybe 2000 volts. Effective protection does not addresses that. And yes, that ethernet port protection is superior to any protector that would be adjacent to electronics.
Best protection, already inside every appliance, must be protected from destructive surges. Those easily blow through that robust galvanic isolation. And also find other destructive paths.
Best protection only exists when a surge (lightning is only one example) does not exist anywhere inside. Then best protection, already inside every appliance, is not overwhelmed. Best protection means destructive transients connect to and dissipate harmlessly in earth BEFORE entering a structure.
As demonstrated by that Tech Note. As Ben Franklin first demonstrated over 250 years ago. Earth ground (not any protector or lightning rod) defines quality and effectiveness of protection.