notes.app: merge separate Notes settings into iCloud

I have a question about the Notes application and how it interacts with iCloud. I have an iPhone and a Mac, and I'm using iCloud in both with the same account.

Many things, like the photos, seem to be totally synchronized between those two locations and iCloud.com, for what I can say.

However, on my iPhone in the iCloud settings, I still have the notes turned off. On my Mac, in the configuration of iCloud, it is activated. As a result, Notes is exactly the same between my Mac and iCloud.com, but on my iPhone it's different.

On my iPhone I have several folders in Notes: "On my iPhone", as well as several additional folders for several different email accounts (for example, Gmail and Yahoo). All folders have different notes in them.

What will happen if, on my iPhone, I activate the Notes in the iCloud configuration? How can I consolidate this? I think that ideally I would like to merge everything to be a single folder, but I do not want to lose any notes in the process. I could settle for just merging the "On my iPhone" folder with what I have on my Mac if possible (the Mac / iCloud.com notes are all in one folder).

Thanks in advance.