Echoing
cool pop's reply!
Agents don't waste time on short works unless there is a commercial anthology involved centered on a theme. I recently bought a Regency Christmas romance collection, each story by a madly popular pro writer in the genre. Unless you are a madly popular pro writer with a solid track record of sales, don't expect to get an invitation from the editor. They are interested in sales numbers and unknown writers don't get invited. Acquire an agent for long works. She will let you know if an anthology is looking for contributors.
OTOH, indie writers can do all right for themselves with short works and lots of them, but they have to make sure not to overprice. A reader will pay .99 for 7500-17,500 words, but not 2.99 for a work they may finish in less than an hour. What you do with the low price point is build an audience of loyal readers who love your writing and buy your new stuff as it's available.
Now, I know of a madly popular mystery writer who has been in the industry since the 1950s. He is an excellent instructor, has won lifetime achievement awards and republished his out of print works. BUT ---- he wants 9.99 a pop, even for novelettes. I love his stuff, but will give that a pass!
Be upfront about length and make sure the work packs a punch in terms of likeable characters and fresh plotting starting with the first line to hook them in the "Look Inside" feature. An idea to aim for is at least 10K words, and translate into a 250 words/page count: 40 pages. Invest in good cover art. I like browsing selfpubbookcovers.com since a bit of art can inspire a story and their prices are reasonable.
The best-selling genre is always going to be "mommy porn."
Ladies enjoy something hot to spice up their lives. Writing these is harder than it looks. Readers can tell when a writer is just phoning it in, and many can even tell if it's a male or female writer slinging the words. Male writers tend to skip over the emotions of a nookie scene and focus on the visual. Female writers tend to include all the senses and feelings.
After that, then regular romance from spicy to sweet also has a good audience. Some readers prefer sexual tension over graphic sex, others want the suspense of a developing relationship. Again, you have to be sincere or they sense it. If you enjoy the story, they will too.
Last time I looked, the overall romance genre accounted for about 50% of all book sales. That may have changed, but it IS steady about being the favorite.
https://bookstr.com/article/book-genres-that-make-the-most-money/
Amazon is picky about genres. If once a book is labeled as erotica there, then it won't be changed. Read their rules and discussion threads thoroughly!