Ukraine

Setting aside the question of whether he's actually going to take the thing into a fight, I don't see how you'd get much more out of it than acting as a technical.

https://en.wikipedia.org/wiki/Technical_(vehicle)

A technical, known as a non-standard tactical vehicle (NSTV) in United States military parlance, is a light improvised fighting vehicle, typically an open-backed civilian pickup truck or four-wheel drive vehicle modified to mount SALWs and heavy weaponry, such as a machine gun, automatic grenade launcher, anti-aircraft autocannon, rotary cannon, anti-tank weapon, anti-tank gun, ATGM, mortar, multiple rocket launcher, recoilless rifle, or other support weapon (somewhat like a light military gun truck or potentially even a self-propelled gun), etc.

Technicals fill the niche of traditional light cavalry. Generally costing much less than purpose-built combat vehicles, the major asset of technicals is speed and mobility, as well as their ability to strike from unexpected directions with automatic fire and light troop deployment. Further, the reliability of vehicles such as the Toyota Hilux is useful for forces that lack the repair-related infrastructure of a conventional military on land. However, in direct engagements they are no match for heavier vehicles, such as tanks or other armored fighting vehicles, and they are mostly helpless against any air support from a proper military. [citation needed]

The Cybertruck is a light truck. It's got no armor, no relevant sensors. It's not tracked, which probably isn't the end of the world. The only notable thing about it is that runs on electricity, but in a battlefield context, my bet is that it's easier to get ahold of fuel than electricity. I guess you don't have to worry about fuel in a tank catching on fire, but lithium makes for exciting reactions too -- I kind of doubt that the battery cases deal well with being ruptured. Militaries are generally using ICEs, not EVs, today.

I'd say that a Hummvee is a considerably-better-suited vehicle in that category, and nobody is going to make a big deal out of taking a Hummvee into a fight.