Can you publish a single chapter of a manga series? I am guessing yes, but I don't see manga chapters being sold separately on Amazon. I see comics issue being sold, but it seems issues are sold for collection purpose. But I don't see webcomics and manga chapters being sold separately. I see them being sold as volumes, roughly 500 pages, so I am wondering how do you navigate this as an author.
I believe you are allowed to sell anything legal on Amazon, as long as you aren't defrauding or misleading people.
Another route is the website "Patreon", people "subscribe" for a small monthly fee of your choice; to support you (including artists), in return for you posting your created content online for them to enjoy. They can cancel their subscription at any time. Most artists post a combination of totally free stuff and subscriber-only stuff. I subscribe to a channel there, for $5 a month.
How you get the word out is up to you; of course. The artist I subscribe to began by posting You-Tube videos; and asking for people to join their Patreon channel.
I'm not sure, but you might be able to sell some intro chapters on Amazon or Apple Store for very cheap or free, and advertise your Patreon channel using those, if not directly then in the content itself. Then you could build yourself a subscriber base. Good luck.