I think you're in the wrong forums - this is a RetroPie specific forum, which is not related with neither of the projects you're mentioning (openelec/retrorangepi).

Retropie has an installation available of Kodi. It is available via the Retropie setup and is a full media center. If you prefer to run a separate install of Kodi on a seperate sd card, use LibreELEC.

Powerblock works fine on Retropie/Raspbian. Open/LibreELEC are embedded systems so if it doesnt work OOTB, it is generaly a pain in the ass to make it work. The support for it should be given by them if they are interested.

@ljm99 Kodi has an add-on called ROM Collection Browser for playing your existing roms. I've never used it, so I don't know how well it works, but I thought I'd mention it.