if you are still open to adding new Metadata Sources
Manga and Light Novels
SevenSeas - https://sevenseasentertainment.com/ (its like yenpress, very large manga and LN provider part of big 4 with Viz, Kodansha and YP)
DarkHorse - https://www.darkhorse.com/ and https://www.darkhorse.com/Zones/Manga (More grittier series and part of DarkHorse Comics which has multiltudes of American Comics)
SquareEnix - https://squareenixmangaandbooks.square-enix-games.com/en-us/series (yes they publish manga, but its small so low prio)
Denpa - https://denpa.pub/ (Manga and arm of Fakku for proper series)
J-Novel Club - https://j-novel.club/series (Mostly LN but has some Manga publications too)
Manhwa exclusive (Official)
Webtoons - https://www.webtoons.com/en/
Tapas - https://tapas.io/
Toomics - https://toomics.com/en
Lezhin - https://www.lezhinus.com/en
DayComics - https://daycomics.com/
Kakao - https://page.kakao.com/
Naver - https://www.naver.com/
Manta - https://manta.net/en
WebComics - https://www.webcomicsapp.com/
Net Comics - https://www.netcomics.com/home
Manhua Exclusive (Official)
Kuikian Manhua - https://www.kuaikanmanhua.com/
Bilbilli - https://www.bilibilicomics.com/
And if you are open to adult sources
R18+
Fakku - https://www.fakku.net/
Irodori Comics - https://irodoricomics.com/new-releases
2D Market - http://2d-market.com/
E/ExHentai - https://e-hentai.org/
Hentag - https://hentag.com/
Thank you
if you are still open to adding new Metadata Sources
Manga and Light Novels
SevenSeas - https://sevenseasentertainment.com/ (its like yenpress, very large manga and LN provider part of big 4 with Viz, Kodansha and YP)
DarkHorse - https://www.darkhorse.com/ and https://www.darkhorse.com/Zones/Manga (More grittier series and part of DarkHorse Comics which has multiltudes of American Comics)
SquareEnix - https://squareenixmangaandbooks.square-enix-games.com/en-us/series (yes they publish manga, but its small so low prio)
Denpa - https://denpa.pub/ (Manga and arm of Fakku for proper series)
J-Novel Club - https://j-novel.club/series (Mostly LN but has some Manga publications too)
Manhwa exclusive (Official)
Webtoons - https://www.webtoons.com/en/
Tapas - https://tapas.io/
Toomics - https://toomics.com/en
Lezhin - https://www.lezhinus.com/en
DayComics - https://daycomics.com/
Kakao - https://page.kakao.com/
Naver - https://www.naver.com/
Manta - https://manta.net/en
WebComics - https://www.webcomicsapp.com/
Net Comics - https://www.netcomics.com/home
Manhua Exclusive (Official)
Kuikian Manhua - https://www.kuaikanmanhua.com/
Bilbilli - https://www.bilibilicomics.com/
And if you are open to adult sources
R18+
Fakku - https://www.fakku.net/
Irodori Comics - https://irodoricomics.com/new-releases
2D Market - http://2d-market.com/
E/ExHentai - https://e-hentai.org/
Hentag - https://hentag.com/
Thank you