a LOT of chapters

http://www.mangago.zone/read-manga/medical_return
http://www.mangago.zone/read-manga/the_second_coming_of_gluttony/
They're pretty damn underrated. Though I'm not sure if they're lengthy enough. You could try Peerless Alchemist, it's pretty good and long.

forever mine
charlotte's letter
thirsty thirty
sica wolf
chongsa
the taming of the shrew
handmade ent.
how about having dinner together?
like a butterfly
suicide prevention commitee
pixel of life
yaonie jiaozhu kuai tang xia
empress of another world
whats wrong with secretary kim
a dimwitted monk fell from heaven
just one smile is very alluring
the young master and the maid
zhiran chenghun
chasing the sun
why did you come to my home/who invited you
salty studio
the stories of those around me
july found by chance
rowdy detective
love me more
too close
the last zombie
stalker's game
the flower that was bloomed by a cloud
rest in peace
a capable maid

these generally have 30+ chapters if that counts as alot ^^ sorry if they aren't niche enough, I don't read that many manwha/manhua

oh and also
lan chi

http://www.mangago.zone/read-manga/cheese_in_the_trap/
http://www.mangago.zone/read-manga/rpg/
http://www.mangago.zone/read-manga/ake_no_tobari/
http://www.mangago.zone/read-manga/a_post_apocalyptic_journey/
http://www.mangago.zone/read-manga/demons_can_t_be_pretty/
http://www.mangago.zone/read-manga/delivery_knight/
http://www.mangago.zone/read-manga/honey_blood_lee_narae/?av=3
http://www.mangago.zone/read-manga/eunsuk_jung_gu/
http://www.mangago.zone/read-manga/nejimaki_seirei_senki_tenkyou_no_alderamin/

http://www.mangago.zone/read-manga/the_best_wolf_in_my_life/
http://www.mangago.zone/read-manga/the_lady_and_her_butler/?av=2
http://www.mangago.zone/read-manga/doridosim/ http://www.mangago.zone/read-manga/what_s_wrong_with_secretary_kim/
http://www.mangago.zone/read-manga/kijima_kun/

ε=ε=(ノ≧∇≦)ノ OMG!!Thank you so much everyone (≧∀≦) Now I have things to read during quarantine (๑•ㅂ•)و✧