Custom file type is not showing "Open With"

Question

I might be going insane, I followed so many tutorials and still my custom file type is not able to be opened within my app -

Here is my custom UTType extension:

extension UTType {
    static let reminderList: UTType = UTType(exportedAs: "com.brettrosen.Mocha.reminder-list")
}

As well as my Transferable conformance:

static var transferRepresentation: some TransferRepresentation {
    CodableRepresentation(contentType: .reminderList)
}

I'm at a loss for why I can share this as this custom file type but there is no option to open with it. I see the data is in json format in exactly how I'd expect it, so I have no idea what I'm missing. Really hoping someone can spot it