Decky Loader (formerly known as PluginLoader) is an open source project written in Python and react (and with support for custom backends other than python!) with the goal of adding plugin-loading capabilities to the Steam Deck. After installing, plugins can be accessed using a plugins tab in the quick access menu.
Decky does not support HoloISO out of the box.
Our installer tool is not tested against HoloISO, we try to maintain a level of support for non-deck linux systems but we do not provide direct support. We'd like to expand our support but don't have the time to do so. We invite pull-requests to resolve such issues.
Also, please note that we have no plans for Windows support via core contributors.