I think I can say I know all about tight jeans. I also belong to several net sites frequented by men with similar fetishes.
Not everyone has the same policy regarding dick in jeans. many of the guys wear tight jeans with no underwear. I myself find that uncomfortable so I always wear something under the jeans, often a thong, sometimes a brief, never anything more substantial. Whatever it is, the important thing is tha the underpants keep my dick and balls held in whatever position I choose to put them in, right, left or centre.
Tight jeans, or any kind of tight pants, will put pressure on the organs, but that doesn't mean it has to be uncomfortable. All material stretches to a certain extent. Even the so-called "moose knuckle", where the balls are visible one each side of the centre seam, does not have to be uncomfortable as long as the seam is not ridiculously tight.