@Airy it is probably not possible to embed individual images into the Mac pushover notifications for technical reasons.
However, if you use Pushover's iOS app, you can add it there for the Apple Watch, iPadOS and iOS
Like in the video in the following post:
With the external plugin, it is possible to insert images via the file path and then display them under iOS, iPad OS and WatchOS.
This is a huge advantage, as you would then have to create your own token for each image on the Pushover website.
Would it also be possible to integrate the selection of “Custom Sounds” like in the plugin?
@noisneil the prerequisite is not to upload an image for the Keyboard Maestro application to the Pushover website.
This makes it possible to display individual images/icon in the KM 11 pushover notifications or the external pushover plugin.
Then create your own API token for the desired image on the website and insert it into the KM 11 pushover notification.
Please excuse me, I just read @JimmyHartington's 2nd post. You're right, this is probably only possible with the external Pushover plugin.
I confess I'm struggling to follow some of this thread, but I may have a different approach that could work. Instead of using a link to an image, why not encode the image directly into the HTML, like the following. Note that there's a command in macOS called "base64" which can convert your image file into the text representation below. The entire string could probably be assembled in a single KM action, which you could then pass to the Pushover action in a single variable. Sounds a lot simpler than what I'm reading in this thread.
EDIT: I just tried it, with HTML code, and both macOS and iOS say "No Message" unless I add additional text to the message, in which case the text appears but the image does not. So both of Apple's OS's are not interpreting this image code. I really had no idea if it would work or not. If this doesn't work, and nobody can tell me what I'm doing wrong, then I can't understand why an external image would work.
P.S. I have no idea what's in the image above, it was just an example base64 image from one of those technical websites explaining how to insert images into HTML code. Hopefully it's just a smiley face.
There might be a way for the KM Pushover action to support images, but the fact that the Pushover.Net service does not support the base64 encoded images means that that's a Pushover.Net problem, because nothing the KM engine can do can fix that particular issue. Once any message is sent to the Pushover.Net server, KM has no further involvement.