Gun Girls have been around for ages. The only difference with Lujan is that she's still a member of the armed forces I guess and previous gun girls didn't have access to creating TikToks or whatever.
It's probably more, she made her account and posted stuff on it and became popular, then the military is like... "Oh she's a popular influencer in the military. Lets support her by having her show up to this training range and fire a howitzer or something."
Like everyone from Team Glock to Black Rifle Coffee Company to the US Army Armor & Cavalry Museum have featured female influencers with interests in guns or tanks or military wargaming before and have been given access by the Pentagon to stuff as good PR.
Sure you can frame it as a clickbait like that video did but it's probably no different if NASA promotes 'Science Girl' or Simone Giertz or something. They're not pre-programmed astroturf or some masterful conspiracy.
If she is though, good job boosting her by spreading awareness lol. I never heard of her until reaction videos with the same title kept showing up in my recommendations.