On reddit, one can simply type u/me or r/reddit - I can see mentions of /u/user or /c/community in descriptions but doesn’t seem to mention a sublemmy like a subreddit.
Also, can’t seem to share a Lemmy Profile with their URL like for mine as example.
User mentioning syntax:
@<username>@<domain.tld>
Community mentioning syntax:
!<community>@<domain.tld>
Bonus:
Image embedding syntax:
![ [name] ](<url>)
…
I’d also advise you to read this community’s rules, I locked your post because of rule 5.