I’ve heard someone else say something about Ilford XP2 (C41 colour process) that it can be rated at any ISO?
xp2 is a lovely film. Makes 35mm look almost like medium format with it’s smooth tonaity and non-existant grain. I’ve found it best exposed at around 200 and developed normally. Any higher and you start to lose shadows and the grain (dye clouds really) isn’t nice in the same way a traditional bw film is.