I don't think it's tty1 that's hardcoded, but /dev/fb0. See open_terminal in ubiquity/bin/ubiquity-dm.
If the serial terminal isn't sufficient to support dialog, it may be worth trying DEBIAN_FRONTEND=readline.
I don't think it's tty1 that's hardcoded, but /dev/fb0. See open_terminal in ubiquity/ bin/ubiquity- dm.
If the serial terminal isn't sufficient to support dialog, it may be worth trying DEBIAN_ FRONTEND= readline.