After hours of work using a Sandisk Flash drive and a Seagate Ext. SSD and meticulously following guidance from various websites; nothing works; last couple of efforts got a msg. along the lines of "drive not recognized. The closest I got was using the ChromeOS /hybrid from "Neverware" which at Boot resulted in a small white rectangle in the middle of the screen and a more colourful small one at top left. So has anyone ever managed this; the guides don't actually state that its ever been done; I doubt whether I'll ever try such a thing again; I suspect however that it may be as simple as that Monterey requires some new format of the drive; the Ubuntu guide states MSDos-FAT which sounded odd (to a layman).