Save AS PDF-can layers be created?

Well, there is no layer support in FrameMaker so you can't directly export layers nor can you just add them after the fact in Adobe Acrobat. You can—as you correctly noted—export existing layers in InDesign to a pdf, as well as from Illustrator and in Photoshop.

That said, in looking for a potential workaround for FrameMaker, this may have  potential—but I haven't tried it.

Import layers (Acrobat Pro DC)

You can import layers from a PDF or image file into a target PDF. Supported image file formats are BMP, GIF, JPEG, JPEG 2000, PCX, PNG, and TIFF.

1. Click the Layers button in the navigation pane.
2. Choose Import As Layer from the options menu .
3. In the Import As Layer dialog box, click Browse and locate the file to import. If the source file is a multipage document, enter the page number you want to import in Page Number. If the target file is a multipage document, specify the Target Page Number in the Preview section of the dialog box.
4. Select one of the following import options:
   1. Create New Layer: Creates a single, separate layer from the source document. Enter a name for the new layer.
   2. Add To Group: Specifies the existing layer group in which to add the imported layer. This option is available only when the target PDF contains one or more existing layer groups, and when Create New Layer is selected.
   3. Add To Existing Layer: Adds the content from the source document to an existing layer in the target document. Select a layer from your target document. The imported content will have the same layer properties as the existing layer in the target document. This option is available only when the target document contains layers.
   4. Copy Layers From Source: Imports the layers from the source document. This option is available only when the source document contains layers.
5. Adjust the Position and Appearance settings as needed, and then click OK.

—PDF layers, Adobe Acrobat DC

I wonder if you could create a conditional text document in FrameMaker, and export the various versions to individual pdfs, and then import them into 1 PDF as individual layers? My concern would be with step number three, which sounds like it might indicate that this is single page only, which would be a lot of work for a long Fm document.

If you give it a try, please come back and let us know if that works. Otherwise, I'd head over to InDesign.