There’s a good amount of enjoyable short bls, but it’s pretty hard to find short cool action ones personally. Here’s a few bls:
https://www.mangago.me/read-manga/mayonaka_no_ore_wo_mite/
https://www.mangago.me/read-manga/kwak_ha_jun_s_observation_diary/
https://www.mangago.me/read-manga/merry_on_the_rocks/
https://www.mangago.me/read-
manga/non_refundable_alpha/
https://www.mangago.me/read-
manga/bitten_by_moonlight/
https://www.mangago.me/read-manga/go_out_with_me_too/
https://www.mangago.me/read-manga/regression_in_3_seconds/
https://www.mangago.me/read-manga/so_who_got_screwed/
This one is a series, but I didn’t put all of them here
https://www.mangago.me/read-manga/kedamono_arashi/
The short ones are usually the good ones and it sucks when you realize it’s one of those less than 10 chapter ones. Hope you get better soon

I'm kinda sick & would love some recommendations for simple short stories since my brain is fried, mostly bl or action as those are my favorite things to read/most read stuff