Zombie GLs:
https://www.mangago.me/read-manga/chimidoro_ice_cream/
https://www.mangago.me/read-manga/black_backed_albatross/
https://www.mangago.me/read-manga/zhi_wei_jie_kai_ni_de_jia_suo/
https://www.mangago.me/read-manga/stitch_you_together/
https://www.mangago.me/read-manga/the_subjugation_school_life_of_the_corpse_girl_and_the_love_heavy_knight/
https://www.mangago.me/read-manga/your_head_s_fallen_off_again/
https://www.mangago.me/read-manga/my_first_friend_was_a_zombie/ (bullying, violence)
https://www.mangago.me/read-manga/yuri_of_the_dead/ (one-shot)
https://www.mangago.me/read-manga/a_zombie_and_her_master/ (one-shot)
Apocalypse GLs:
https://www.mangago.me/read-manga/isekai_picnic/
https://www.mangago.me/read-manga/the_iron_inside/
https://www.mangago.me/read-manga/garan_no_hime/
https://www.mangago.me/read-manga/goodbye_dystopia/
https://www.mangago.me/read-manga/erio_and_the_electric_doll/
https://www.mangago.me/read-manga/us_the_end_of_the_world_and_the_rest_of_our_life/
https://www.mangago.me/read-manga/tatoe_sekai_ga_owattemo_watashi_wa_kanojo_wo_erabanai/
https://www.mangago.me/read-manga/kodoku_no_kochou_wa_donna_yume_wo_miru_no_ka/
https://www.mangago.me/read-manga/stellar_step/
https://www.mangago.me/read-manga/the_rules_require_me_to_love_you/
https://www.mangago.me/read-manga/i_don_t_really_miss_you_i_m_in_the_apocalypse/
guys are there any zombie / world ending GL’s.. genuinely can’t find anything