Squaddies is a series (two so far) of short military SF scenarios from Astronautilus Production; I've been a proof-reader on them. They're designed for fairly near-future interstellar settings. How can they be used with GURPS? Pretty easily, I reckon. This post deals with equipping the troops.

You'll need GURPS Ultra-Tech, which I think has often been underappreciated; it was one of the first sourcebooks for 4e, and while it has rough spots I think it does a good job overall. TL9 seems most appropriate, with very limited superscience: on the ground, rather than in space, it looks quite like a contemporary war but with more gadgets. I'll note relevant skills, because this will affect character design.

This isn't a comprehensive listing of everything that soldiers might carry, use, or come up against, just some of the things I think are particularly relevant.

Weapons

The preferred long arm is very clearly the Storm Carbine (Guns/Rifle); it's a little heavier than the Assault Carbine (that might be issued to airborne troops), but it has rather more punch, and the larger bullets are more effective at wounding once they've got through armour. (Note the errata, though; it's only pi+ damage, not pi++ as in some printings.)

If you want to load down your characters with extra gear, give them a few magazines of variant rifle ammunition: 10mm explosives are too tiny to be really useful, but some sort of armour-piercing round is probably a good idea.

One might reasonably expect 2-3 hand grenades (Throwing), typically HE and smoke.

Add to one or more troops per section, depending on doctrine, an underslung 25mm grenade launcher (Guns/Grenade Launcher), with HE, concussion and/or shaped charge rounds for it; this will replace the hand grenades.

Infantry in this setting are more important than armour, and one justification for that may be giving every trooper an IML or two (Artillery/Guided Missile) if training time allows them to become competent - they're only 4lb each and with a shaped charge warhead they'll cripple a light tank if they hit. (Though the tank's anti-personnel chaingun has longer range, so the missileer will still need to be clever.) In a more conventional version of the setting these missiles will be limited to dedicated anti-armour units.

In generally increasing order of frightfulness per shot and decreasing order of number of shots, the support gunner may have a 7mm light support weapon (Guns/Light Machine Gun), 25mm payload rifle (Guns/Rifle), 40mm grenade launcher (Guns/Grenade Launcher), or an MLAWS launcher (Artillery/Guided Missile). Any of these may gain an articulated weapon harness for use on the move, but the LSW particularly benefits from it. With this array of weapons available, it may make sense to have one support gunner per fireteam, and two different support weapons per section.

If you have access to Pyramid #3/37, Tech and Toys II, the 64mm Commando Mortar (Artillery/Cannon) is an ideal addition to the support-weapon list. That issue also includes a number of artillery pieces from which PCs can call on supporting fire.

Snipers, if assigned with the unit, will carry an anti-materiel rifle or just possibly a sniper railgun (both Guns/Rifle). Officers will have a 10mm heavy pistol, 15mm magnum pistol for the cowboy types (both Guns/Pistol), 15mm gyroc for the techno-cowboy types (Guns/Gyroc).

Non-lethal weapons will include electrolasers (Beam Weapons/Pistol), tanglers (Guns/Pistol), nauseators (Beam Weapons/Pistol) and vortex guns (Liquid Projector/Sprayer); all of these are bulky enough that they probably aren't carried unless police work is expected. All except the tangler also need special training to use effectively. A good compromise is probably to add some launched or thrown tangler or gas grenades to the armoury, and swap them into the loadout when the mission seems to demand them.

Melee isn't a big part of this kind of setting, but someone who cares may well have a superfine knife (Knife). Police and prison guard types may have stun wands (Boxing, Brawling, Karate or DX) or zap gloves (Shortsword).

Defences

The typical rig is a reflex bodysuit base layer, with a reflex tactical vest (with optional trauma plates), assault boots, and a visored light infantry helmet. Heavier armour for non-mobile forces is a combat hardsuit, but that's too heavy for troops who have to go any distance on foot.

All this means that the typical trooper with bodysuit, vest and trauma plates has DR64 on the torso, which makes them proof against storm carbine fire. On the other hand they only have DR18 on the head, and DR12 on the arms and legs, which will stop fragmentation but not aimed fire; and if the enemy fires APHC ammunition, some torso hits will still be damaging.

Communications and other electronics

The backpack radio (Medium Radio communicator) has a base 100-mile range. Depending on fine details of setting, everyone may have a Tiny communicator (1 mile) built into their helmets, or not; that may not have the top-grade encryption offered by the long-range radio. Everyone is likely to have media players, book readers, etc., quite possibly all rolled into a single smartphone-style device.

Basic low-light binoculars offer 64× magnification and Night Vision 9, while the thermal version drops to 16×. Sometimes forces may be equipped with low-light or thermal faceplates on their helmets. Hyperspectral sensors are really expensive but a rich officer might have one.

Chameleon surfaces are probably too expensive to give to everyone, but special forces may well be nearly as invisible as their reputation would have it, with thermo-optic chameleon cloaks.

Medicine

Bandage spray is in every soldier's kit (probably in a standard location so that your mates know where to find it on you when you've been hit). Medics will make heavy use of it too, and there are automeds and diagnostic beds back at HQ. If you live long enough to be evacuated you'll probably make it.

Vehicles

The Armoured Hovercraft is a good match for the typical APC wanted in this kind of scenario: decent speed and reasonably proof against small arms, though it's mincemeat against anti-armour weapons. For a wheeled or tracked equivalent you could reduce the speed and put up the armour a little bit. For air transport, the Utility Vertol works for small units, and the tiltrotor for larger ones; both are woefully under-armoured but the vertol can dodge effectively and could have door guns added. There are no ultra-tech helicopter gunship stats in GURPS 4e at the time of writing.

The Light Battle Tank makes a good threat.

If you have access to GURPS Spaceships 4: Fighters, Carriers and Mecha you may find the Valkyrie-class dropship useful: it can carry a single Armoured Hovercraft or Tiltrotor Transport, or two Utility Vertols.