Denis

Ubuntu 22.04

Hit 'e' in Grub to edit boot kernel parameters. Add console=tty0 console=ttyS0,115200n8 to the kernel line :

linux    /linux --- console=tty0 console=ttyS0,115200n8

Ubuntu 20.04

When the boot: prompt appear, type live console=ttyS0,115200n8 vga=none

(Apparently, it could be gfxpayload=text instead of vga=none on Debian 12)