https://pluralrespect.neocities.org/ is a resource that lists itself as sort of a "place to go after seeing https://morethanone.info/ ".
Plural Respect gets into the topic of sysmedicalism, too, but I want to make a comment on it myself.
I personally compare being plural to being queer, in the sense that in the end it's about finding a way to define your identity in a way that makes sense to you, it works out for everyone at least a little bit differently, and there's not really a wrong way to do it (unless it involves dictating or gatekeeping other people).
As an extension of that, I see sysmedicalism as comparable to transmedicalism. Just as transmedicalism indicates that you're not really transgender unless you fit the medical definition of it (gender dysphoria, undergoing medical treatments, etc.), sysmedicalism indicates that you're not really plural unless you're diagnosed with DID (dissociative identity disorder) as following certain guidelines.
While there are some trans people who see a medical diagnosis as central to their identity, and there are systems who see DID as central to their identity, it is my firm belief that seeing medical diagnoses as fundamental to everyone's identity is reductionist and harmful. In addition to giving control of the definition of "trans" and "plural" to people who are largely not either of these things, it also defines these experiences fundamentally on trauma, when there are so many things that are cool and fun about being trans or plural, and serve as better guidelines for exploring oneself and coming to clearer pictures about who you are, who you want to be, and who you can be.
So if I were going to give a short message to anyone realizing they're plural, I do think the resources are a good idea, but my first message to them would be this: Don't worry about the doctors. Listen to other plural people, and listen to yourself. Those two things should take priority.