Some of the installation / OTA payload generation scripts require the default Python to be Python 2.7.
As long as you install Python 2.7 and set your default Python to be 2.7 (through update-alternatives for example), it should work fine.
We regularly flash and even generate flashable images for AGX Xavier from Ubuntu 20.04, 22.04, Debian 12 and even Debian unstable.
That’s for Xavier generation devices.
For Orin devices and the new flashing script we are unfortunately still bound to Ubuntu 20.04 as we haven’t identified the issue preventing flashing to succeed on less obsolete systems. There seems to be something not correctly initializing the IPv6 link local config on the USB gadget interface used during flashing and relying on a default config that is not the same with newer kernels. Hope to have soon time to track this issue again so we won’t be required to keep an old Ubuntu 20.04 machine just for flashing Orins purpose. That’s only for Orin, not for Xavier.
Hope that helps.