> ... but my understanding is that meditation techniques often feature closing your eyes and focusing on breathing, body parts or some other irrelevant thing

It's more like the opposite. If you think about your breathing, you'll be "controlling" it (which funnily enough is not the case when you don't think about it). Meditation is the opposite: you have to be in a state where you can think about your breathing and yet you're not controlling it.

I can tell that, from doing it since a long time and from talking to people about it, even many people who practice meditation cannot reach that state (thinking about breathing without controlling it).

And you also really don't focus on body parts: you "disconnect" them all until you don't even feel them anymore.

And you also shouldn't focus on irrelevant things: you have to focus on absolutely nothing.

There are many different techniques to "pass on through to the other side": some visualize thoughts ("words" or the "internal monologue") as if it was a sea. The more thoughts, the more hectic the sea (and you want it all calm: no words, no internal monologue). Some imagine a lotus flower opening and when the last leaf opens, you can be in. Some imagine diving.

I meditate on and off since a long time. There are benefits, for example I definitely can lower the intensity of headaches (or at least how I perceive the pain). What I tell my friends is that Buddhist monks are actually on serious trips beating any psychedelic drug that does exist.