I can say that I use to test Monterey in an external SSD, but connected to a SATA port via Pcie. In the final boot, the volume "Macos Installer" (or something like that) does not appears. Same drive, connected to USB, and do appears. Then I can continue the installation.I had this happen to me when testing Monterey, but only on an external SSD, never the internal drive. I've always suspected that it has to do with the wrong partition being chosen when the system performs a reboot during the upgrade process. The update (as well as the clean installation) creates what appears to be a temporary partition that is used as the installation media during the install process. But if this partition is not chosen at boot time then the system boots the default OS partition. After a prolonged wait the systems seems to wipe any traces of the attempted system update. I've managed to get around this issue by waiting for the partition selection screen to show up in OCLP when the system reboots for the first time, there choosing the installation partition, after which to installation proceeds as normal. Never once have I been low on drive space. But perhaps I misunderstood the failures you were referring to.