These two I can think at the top of my head that are in some sort of webcomic form at the moment:
http://www.mangago.zone/read-manga/i_favor_the_villainess/ (gl)
http://www.mangago.zone/read-manga/to_be_or_not_to_be/ (bl)
These two are adapted from a webnovel and there is other webnovels that are gl and bl isekai stories.
Not exactly a BL but the gay tensions are high (๑•ㅂ•)و✧
http://www.mangago.zone/read-manga/a_mild_noble_s_vacation_suggestion/
Dude gets transmigrated into a BL world as a mob character: http://www.mangago.zone/read-manga/zettai_bl_ni_naru_sekai_vs_zettai_bl_ni_naritakunai_otoko/
ISEKAI X BL
list is a collection of
• tt to past
• tt to future
• parallel dimension
• reincarnation
• transmigration
• transportation
http://www.mangago.zone/home/mangalist/744197/
Follow the list to be updated. And if you liked the mangas/manhwas I included, please do recommend. Enjoy~ (人 •ᴗ•)
http://www.mangago.zone/read-manga/isekai_trip_sex/
http://www.mangago.zone/read-manga/liebling/
http://www.mangago.zone/read-manga/trip_lovers/
http://www.mangago.zone/read-manga/the_titan_s_bride/ (huge light saber)
http://www.mangago.zone/read-manga/heaven_official_s_blessing/
http://www.mangago.zone/read-manga/scumbag_system/
http://www.mangago.zone/read-manga/heaven_hell_roman_company/
Feel like ive read almost all the good shoujo isekais and it made me wonder if theres a bl/gl of the genre.... wanna see them fuck the universe up but make it gayer