Tough situation, for sure. In the short term, the internet is a decent way to connect. (I found my people through the furry community, which has a vibrant community across every state and many countries. Many are queer, the conventions are a blast of old-school fun, and many are all-ages (if a parent or guardian tags along). Many furry communities are on Telegram, usually with state and city groups, even in very rural states. This is meant more for mid teens and up/stranger danger/YMMV, but it's how I've met tons of lovely people in new cities whenever I've moved.)

Though the Trevor Project is more geared towards helping people under 25 through tough times, they might have some sort of pen pal program, which might be good for a kid who is in a remote area.

If his family knows about him being gay and is okay with it, going to a pride event in a city is also a way to start connecting with people like him. If he has a library card, there are programs like Overdrive that can allow you to digitally borrow gay books- though this depends on your library branch. Places like Montana may have some.

Sometimes, cities nearby will have pride organizations at the city or state level. These are a good way to make a first connection to gay people within the state. If you aren't sure how to find these, look for a pride parade- these orgs tend to sponsor them and are always looking for volunteers. They also might have stuff like zoom meetings or are open to answering questions for youth.

Life can be hard as a kid. Much harder still, if one is queer. Generally, though, life gets better as you get older. If he has the means to eventually go to a university or the means to move to a bigger city when he's college-aged, I recommend it.

Edit: I also like the advice below. I remember being starving for knowledge when I first came out. But I also think you shouldn't put too fine of a point on your sexuality too. Like others have said, have fun, make friends, have some hobbies- dating can come later. Plus, the best dates happen when they evolve from an already healthy friendship anyways. :)