You mean push api from webserver?
I don't know if web browser on Kobo supports necessary javascript or whatever protocol, but if not, you can definitely whip something else together with all the tools available (KOReader terminal, shell, lua, wget, cURL from NiLuJe kobostuff, fbink, vnc, Xorg in chroot...many ways to skin a cat!)
http://www.mobileread.mobi/forums/sh...d.php?t=348481
http://www.mobileread.mobi/forums/sh...d.php?t=299110
https://www.mobileread.com/forums/sh...d.php?t=254214
Here's a server implenentation in php:
https://koditi.my/php-sse-example/
Here's a client example using cURL:
https://jvns.ca/blog/2021/01/12/day-...and-a-fun-bug/
Here using python (optionally available from kobostuff):
https://stackoverflow.com/questions/...ing-sse-events
*Edit -whoops, just realized I may be overcomplicating - you just want to dump a server image to client,so..,
https://www.cyberciti.biz/faq/how-to...-shell-script/
https://serverfault.com/questions/24...-a-remote-copy
...and transfer server image to screensaver folder?
UPDATE:Speaking of thinking outside the box, I see this guy went the opposite way, pushing from client to server - makes sense if you have no browser with javascript.
https://github.com/tylpk1216/KoboPageTurner
https://www.mobileread.com/forums/sh...=345507&page=4
***
CORRECTION: According to Sherman, at least some server events are supported on the Kobo browser:
https://www.mobileread.com/forums/sh...d.php?t=330150
https://www.mobileread.com/forums/sh...8&postcount=11
The example I had previously tried was maybe too demanding (you can find the link at the bottom of this post:
https://www.mobileread.com/forums/sh...7&postcount=52
https://www.javatpoint.com/html-server-sent-event
You can see it's pretty challenging even on a low end phone.