Even if you do not have a IIIF server at your disposal, you can still use pb-facsimile to display static images hosted either in your local TEI Publisher instance or on an external webserver. Key is to set the attribute type="image" on pb-facsimile and provide the correct base URI for resolving image links. For an example, we may use the static images used by TEI Publisher on the main start page (e.g. playground.png). Those are stored in the data collection of your local TEI Publisher installation and you could simply add your own images there (or into a subcollection).
To configure pb-facsimile, you just need to set type="image" and change the base URI to point to the root of your TEI Publisher install:
<pb-facsimile type="image" base-uri="http://localhost:8080/exist/apps/tei-publisher/" default-zoom-level="0"
show-navigation-control="show-navigation-control">
</pb-facsimile>
Within your ODD transformation, you could then output a pb-facs-link wherever you want to reference an image, e.g.:
<pb-facs-link facs="playground.png">Playground</pb-facs-link>
This does not differ from using IIIF - just that images will be resolved statically against the base URI instead of going through the IIIF protocol. pb-facsimile will still allow you to zoom into the image and pan it with the mouse.
For sure, images can be hosted anywhere and do not need to be stored on TEI Publisher. Just change the base-uri to point to the base URL you want to retrieve images from.