Part of the January Sale at MightyApe.
Only Physical PS4 version on sale. But even if you buy the PS4 version once you put the disc in a PS5 it will allow you to download the PS5 version from the store free of charge.
You then just have to insert the PS4 disc when you want to play the game on PS5.
$28 at EBGames for both PS4 and PS5. https://www.ebgames.co.nz/product/ps4/263166-scarlet-nexus