Xephyr - no gpu acceleration?

I am making heavy use of Xephyr for x11 isolation. However,acceleration does not work at all. 3d programs simply do not run, video decoding does not work, vdpau does not work, things like chromium and other things bloatd with gpu using web crap are unusably slow. I am using it like this. Xephyr -br -ac -noreset -screen 800x600 :1 DISPLAY=:1 icewm What is the issue? It's the same for when I set it up with doas or sudo.