I have a meta question for you! What do you think the range is on an average elf for óswanë? Like think your average archer or something; someone who is used to using it often, but doesn’t obviously have the power and skill that could be found in Thranduil or Celeborn and esp not Elrond or Galadriel.
iirc in all my research about óswanë I either couldn't find a range limit, so to speak, or Tolkien basically said that distance has absolutely no effect on it. This is with the caveat though that I still have yet to get my hands on a full copy of HoME so I don't know if there's anything in there that might inform my answer better! In Osanwe-kenta Tolkien does say that all Ainu and "Children of Illuvitar" are capable of Osanwe, but ease and skill are (presumably) another matter entirely.
I have this vague idea that it is a trained skill with varying levels of aptitude. I headcannon Elrond has increased aptitude due to the ainur genetics. Ainur exist like, mostly as ideas, right? They can choose to take on fana but they're basically just spirit and idea, so it makes sense to me that communication via thought would feel the most natural to them.
Galadriel does seem to be the most skilled from what we see in the books, and we know that she learned a lot of her arts from Melian.
Tolkien also does mention (iirc) that a person cannot be communicated with if they don't want to be. So there's no forced óswanë within canon. Like, Sauron can't just break into someone's mind even if he wanted to. I tend to fudge that a lot for fun plot and whump purposes. I think it's more entertaining if óswanë boundaries can be crossed without a person necessarily consenting, but this seems to explicitly be something that Tolkien said doesn't happen within canon. Tolkien also writes that there are specific criteria that need to be met for communication to be possible. Affinity between minds is a factor, whether through closeness, love, intimacy, etc. The urgency of the matter to be discussed is a factor, and authority is also a factor (like if a person is trying to communicate to their subjects, or if someone has a duty to another person, stuff like that). If the criteria aren't met then communication can be 'fuzzy', essentially.
Anyway hopefully this is helpful! This is a very belated and long-winded answer haha. So yeah distance really isn't a factor, but skill and aptitude may be.