This is a really excellent thread to read, and reassuring at that too. I think there's a lot of norms that we build up when to comes to non-romantic male relationships, and I fear it stops a lot of meaningful connections from being made.
I'm bi, so I guess I don't fit the exact direction of this question, but most of my meaningful interpersonal relationships have been with men whom I share absolutely no romantic feelings. I think it's really important to know that you can have really potent non-romantic feelings towards someone and it doesn't need to imply any romantic connection. Going on road trips talking with friends about where our lives are going, having friends text you out of the blue to ask how things are, or how a date you mentioned in passing a week ago went, walking around your hometown with your bud just talking your way through some intense mutual pain; that stuff is important, and I fully believe it'll make your life more fulfilling to have those moments with someone, and not just wait until there's a significant other in the picture, or if there is then to avoid leaning on your SO for 100% of all interpersonal closeness.
If there's one thing I'd like to add to the conversation too, it's that I've seen more than a few of these stories share one particular anecdote of closeness followed by "then we never mentioned it again and went back to normal". In the end, only we can judge what we want our relationships to be, so make that choice for yourself, but I'd implore anyone in those cases to consider whether, if that moment felt useful or comforting to you, you should actually strive to not go back to "normal", but instead open up communication with them a bit more at times, and try to be open and close with them, and have more moments like that.