is it okay to post original content here?

[Exxodia]

i guess there's pixiv but its not really popular here? or only official manga is allowed here?

 

[TsuguRaku]

You can post original content, be sure to tag it with the format "User Created"
Some examples :
https://mangadex.org/title/49720/hungry-cat-kyuu-chan-fan-comic
https://mangadex.org/title/45790/dragon-claw/chapters/

 

[blackyawgdom]

If you created it, ask admins in discord. If you translated a one page thing l from an artists pixiv/fanbox, no. Unless it's a 4koma type series (for example https://e-hentai.org/g/1577448/32e693d17c/ )and not oneshot type thing.