nostr:npub1hemdxvjcfz0zt39ymgxwv77k5vrr4tkk25zzg486e4t8sw5rwyksafrq92 if you google "80x25 mode" the first thing that comes up is VGA text mode, but was found across a range of IBM compatibles. heavily associated with IBM in the popular mind, and what i had in mind. so we're talking computer screens here.
you would emulate non-square pixels because they were intentionally non-square, and to get the right aspect ratio on modern square-pixel systems, you need stretching.
PAL did not have an aspect ratio of 5:4. the screens were 4:3 but the way it's usually encoded digitally (720x576) looks 5:4, i.e. horizontally stretched pixels, as opposed to the vertically stretched pixels of many early computer and gaming systems.