I'm going to be honest with you. I think the first thing you need to do before anything is to take a break and just chill. The rest of this will mostly just be speculation and based on my own experiences, but I'll include that as well.
You don't have to continue to post chapters on a daily basis. Usually, it is highly recommended that you only ever post half of what you can comfortably write on a consistent weekly basis for others to read each week. The rest should be kept in a backlog so you can still post updates even when you feel burnt out or otherwise need a break. Even if you have established a pattern of behavior, all you have to do is update your readers to let them know you're cutting back on the updates and when to expect the next one. I only post one chapter a week, but most of the more popular authors I know still only post three free chapters a week and still retain their followers. Some people will still leave, but it's usually not purely because of how often you post unless it is less than once a week and the story seems abandoned or unlikely to be finished. Some follower loss in natural as people slowly read your work and discover whether it suits their tastes or not, you shouldn't panic about it.
While there is sometimes a loss in readership when you try to monetize your writing, very little of it usually has to do with the monetization itself as much as it does with execution. I don't know what methods you used, but the most common way of doing things is to have a set schedule for free updates with a backlog of early-access chapters available on Patreon. You then write and replace the backlog as you post the free chapters so the backlog stays at a consistent number, or, even better, continues to grow. Usually, people charge about $5 and offer 2-3 weeks of early access chapters, but the really popular authors can get away with a mere five early access chapters being available at a time. Since they post maybe three free chapters a week, they only have to write three chapters a week to replenish the early access chapters. Most still end up writing more, though, as they don't want to be stuck working on the same project forever.
You most certainly can publish your other finished work to whatever sites you want. There is a very small percentage of carry-over of readers from one series to the other, though, so it won't really help your issue if people get tired of waiting for updates for their favorite story. However, I would like to note that AO3 isn't really meant for original work and you aren't allowed to advertise monetization at all because it can get the site in trouble and they'll delete your account. Since it is primarily for fanfiction they are very strict about that sort of thing because monetizing fanfiction can get everyone in trouble. Even if it is original work, which they really don't recommend you post there, you still can't advertise Patreon or anything else there. ScribbleHub is different since it is geared towards hosting original content.
I don't know if you should give up and say your work didn't sell quite yet. Depending on how you tried to publish them and make money off of them as well as if they were in English or not, you may just need to try a different strategy. Personally, I use Draft2Digital as it lets you publish to more than a dozen sites while managing everything on their site. They do take a portion of the royalties, but they handle the distribution for you and are mostly reliable. It is still recommended all of your work be available in English, though. Also, it is worth noting that keywords matter and that people will expect you to have maybe a dozen books and to really build your readership for a few years before you will get reliable and consistent sales. Without advertising, some people consider self-publishing to also be a bit like a lottery ticket, but my work has sold without adding Amazon with a little over a dozen copies being sold across ten books after two weeks, most of which I had to wait for the books to go live. Draft2Digital requires your work not be available for free anywhere to publish to Amazon for you and you have to fill out a special application and wait for everything to be approved. I only have three series that aren't available at all elsewhere right now and I have to wait for my tax info to be verified first, so that's why I note that Amazon isn't included in those numbers. Amazon is still number one for distributors, but a lot of the other sites are also good to publish to.
