What is HoloISO?
[HoloISO] attempts to bring the Steam Deck's SteamOS Holo into a generic, installable format, and provide a close-to-official SteamOS experience. Main point of this project focuses in re-implementing proprietary (as in runs-only-on-deck) components that Steam client, OS itself, gamescope and user-created applications for Deck rely on. -https://github.com/theVakhovskeIsTaken/holoiso
Log into the ProxMox web UI Select a storage from the left navigation pane to download the .iso to Select ISO Images in the left sub-navigation pane If running ProxMox 6, download HoloISO Download and upload it to the ProxMox ISO image library If on ProxMox 7, click Download from URL and paste the download URL from above > Click Query URL > Click Download Right click the ProxMox node name > Create VM Give the VM a unique ID and Name > Next On the OS tab, Select the HoloISO installation .iso file, leave the Type as Linux and the Version as 5.x - 2.6 Kernel > Next On the System tab, set the BIOS field to OVMF (UEFI), Check the Add EFI Disk checkbox, Uncheck the Pre-Enroll Keys checkbox, Machine field to q35 and the SCSI Controller to VirtIO SCSI > Next On the Hard Disk tab, set the Disk size to 16 GiB or more > Next On the CPU tab, set Cores to 2 or more and Type to host > Next On the Memory tab, set the Memory to 8192 or more (Must be at least 8 GB to reach the installer desktop environment) > Next Leave the defaults on the Network tab > Next Verify the summary and click Finish Select Hardware from the left sub-navigation menu A physical GPU passthrough is required to run SteamOS and games (A full tutorial can be found here ) Passthrough a USB keyboard and mouse by clicking Add > USB Device > Select the USB device(s) or port(s) to pass to the VM Right click the HoloISO VM in the left navigation pane > Start Press Enter to select SteamOS installer Wait while the SteamOS installer initializes Once a desktop environment displays, double click the Install SteamOS icon When prompted, select Installation type #2 deck-experience > Click OK Select sda from the list of available disks > Click OK Select Erase entire drive > Click OK Click Yes to confirm the installation When prompted, enter and confirm a root password Enter a username and enter and confirm the user's password After the HoloISO install completes, click the Applications menu > Shutdown > Shutdown In the Proxmox web UI, select Hardware from the left sub-navigation menu > Double click the CD/DVD drive > Select Do not use any media > Click OK Right click the HoloISO VM in the left navigation pane > Start The initial boot will sit at Loading initial ramdisk... for a few moments, be patient Select a Language Select a Timezone Select Wired connection 1 Wait while SteamOS downloads and installs updates The VM will reboot Log in with an existing Steam account Welcome to HoloISO / SteamOS 3 Holo
A full tutorial for passing a physical disk to a VM can be found here