For example: I am creating a real estate flyer and want to save it for an agent as an interactive PDF. This way the agent only has to change out the pictures and text for each home.
I do not think that is possible and if it is, most non tech oriented people will have difficulties updating it, even if it is via PDF. I have never seen such feature in a PDF. However there are online platforms such as https://readymag.com that will allow you to create a template, where people will be able to swap out the images and export it as PDF. If that does not work I would suggest looking into web based templates.
It essentially is possible. However, the main work would better be done in Acrobat than InDesign. You can place form fields in the "interactive PDF" document in InDesign, including button fields at the place where the images should go.
If you want to use simple text fields, be aware that you then specify all text properties for that field; if multiple text properties are required within the same field, you'd have to set the richText property, and give better instructions to the user on how to use the tool.
For the images, you are using Button fields, where you can import the image as icon. There are tutorials on the Adobe Community site, which show how to proceed. Note that in order to load your own images, either Acrobat, or Reader XI or newer must be used, and if Reader is used, the images have to be in PDF format.
So, absolutely feasible, within the capabilities of a form.