As mentioned, with the current situation siblings are not considered immediate family (only parents, spouses and children of a PR/Canadian citizen are considered immediate family).
Also, even if siblings were included just coming for a visit will probably count as non-essential travel and you would be rejected anyway. "Reuniting with family" is in my opinion something more permanent and is the wrong words for your case.
My sister wanted to visit me in July here in Canada and we postponed this visit indefinitely now since under the current rules she definitely isn't allowed to visit and it is unknown when the rules will loosen up. I suggest you do the same.
