@Kahomono
No, I don’t believe you can change editors mid-stream. Check out: https://getpublii.com/docs/adding-editing-and-deleting-posts.html
Though if you’ve created or part-created a page or post with say, the Block editor, you could copy the entire HTML, then create a new page with the WYSIWYG editor, choose the HTML code view and paste your code in there. Perhaps give your new page a temporary slightly different name, then save. Check that your WYSIWYG editor page displays okay using Preview. Assuming it does, I would probably just close that page, then go back to your Block editor page version, double-check if there are any other settings you want. If there are, copy those somewhere temporarily — in a plain text file. Then close your Block editor page version and delete it. Go back to your WYSIWYG page version and add in any missing bits, then change the page name back to what you want it to be called. You might want to also check if any SEO settings are correct too.
While the above might seem lengthy, in practice, you can probably do this in about a minute.
