You can run FPP in bridge mode and it works as a standard E1.31 device. You are probably better off taking full advantage of FPP's abilities however and using it as the playback device as well instead of using your PC. As each P10 panel has 512 RGB leds it means that each panel gobbles up 3 universes of data/channels. Sequencing this with Xlights 4 or Vixen 3 would likely be much easier than doing it with LOR. I transitioned from LOR after about 7 years this year and the capabilities of Xlights are amazing. Sequencing the whole house/yard together was something that was beyond LOR (without extras) and having multiple timing tracks was excellent.
If you are already using xLights , then why not cut over completely from LOR ? A number of people have.. and especially if you do it now . I understand that , next year , the integration between xLights and the FPP is likely to be even better than now - and its very good already.
I am not sure about how easy or otherwise it would be to drive large channel counts from LOR in bridge mode.