Seems odd that they supply the saddle with threads but don't stock stuff to bolt to it (just looked at their website). Like you say, stuff they make just clips on.
I'm intrigued (and a bit sad), let me know what you discover.
Prologo came back to me saying there has been a delay in devlopment due to covid, but something is coming. No feedback on when and what exactly, but I suspect it will be just a type of multimount bracket. Probably with Topeak as that partnership is already in place?
I have done some more research and found this:
The Prologo saddle light thing is actually another system that attaches to the top with a clip.
The Specialized SWAT system is actually 60mm apart and fixed with M5 bolts.
Bontrager actually also have a system, mate that works at a Trek store will check dimensions of that. But looks like it is also fixed with M5 bolts.
This will be something proprietary that I just can’t seem to find. Might need to contact Prologo about it directly.