Sure!
First of all, Xeoma can work on ARM devices such as Raspberry Pi and so on. You can
download the distro for ARM here.
Secondly, yes, Xeoma has the RTSP Translator destination module which can stream in compressed h264.
So, download Xeoma to your RPI's, let Xeoma find the cameras, add RTSP Translator to each chain and find these RTSP streams from your Main Server.
Please see if it works for you and let us know if you have any questions!