Here is a list of 50 one shot manga you probably haven't seen yet but wanted to read something light and short!
Some of these have a releasing manga series but it's all rooted from the one shot and not the other way around, either way, if you don't like thr sequel of the oneshot it is still okay to read just the oneshot itself. They are good as themselves. I specifically choose those stand alone oneshot manga for people like me who don't like waiting for an ongoing manga.
stack
Anilist Sync