So, I've got the #Veilid slides, presentation is apparently unavailable.
From a first look, it doesn't seem to provide any particular security/anonymity guarantees that #I2P doesn't.
It does however greatly facilitate ensuring leaks based on services hosted behind the same router can't happen, by essentially giving every application its own router.
Its main gains appear to be facilitation and convenience in modern networks.
The #mixnet use is unclear and the lack of #Loopix-style loop messages seems like a potential problem for cover traffic.
Cover traffic is entirely unmentioned during the entirety of the slides.
It would be possible to build that atop of #Veilid of course.
There are no mentions of delays in messages nor any other manipulation to mitigate timing analysis.
If nodes select routes based on performance, that's an additional deanonymization risk (shared by #I2P).
LisPi
Stefan Prandl