Webdemon slayer's manga ending reveals the ultimate fates of tanjiro and nezuko, although some reading between the lines is necessary to get it all.
Webin episode 14, after getting asked why a demon slayer secretly carries a demon with him, tanjiro ultimately introduces nezuko to zenitsu and inosuke.
Webtanjirou and nezuko's sibling bond is unbreakable, even after nezuko becomes a demon and loses her memories.
Nezuko's evolution as a demon proves her.