Hey friend, same boat (not buying animal products). Sad cause I love sneakers and I love watches on leather straps. I have a couple of ideas for you:
1. ColaReb makes some vegan options such as EcoSuede and one made out of tree fiber. I put the latter on a piece and it actually looks quite nice and feels great. There’s also a material out there called “Lorica” which is synthetic and resembles leather but it’s fairly inexpensive.
2. RubberB has these amazing new straps that are entirely vulcanized rubber but they’ve managed to recreate the feel of a variety of animal textures and I’ve heard some very good things. I plan on buying one of these at some point for a dress piece I have.
3. If it’s an ethics thing, sometimes I buy used animal product straps and it’s less guilty for me, though I acknowledge the validity that the used market props up the new purchase market to some extent.
Hope some of this helps, best of luck.