Interestingly, the 10-lines-of-basic competition, which has been running the last 15 years (https://itch.io/profile/bunsen), has this covered in the rules:
15. If the game is controlled with the keyboard, use "O" for left, "P" for right, "E" for up and "D" for down if possible; this takes into account the most important keyboard layouts (no disadvantages for emulator users with QWERTZ, QWERTY or AZERTY keyboards)
15. If the game is controlled with the keyboard, use "O" for left, "P" for right, "E" for up and "D" for down if possible; this takes into account the most important keyboard layouts (no disadvantages for emulator users with QWERTZ, QWERTY or AZERTY keyboards)