For HYROX, wear lightweight, breathable running clothes and supportive trainers with good grip for pushing the sled. Bring a small towel and water, and gloves are optional for the sled and carries. Chalk is usually available on course. Skip anything heavy or restrictive, since most of the race is running.
This is a direct answer from the CrossFit BC coaching team. Short version first, then the detail and the local context for training in Vancouver. If you want the same answer applied to your own situation, a coach will walk through it with you in person.
Supportive running trainers with good grip work well, since most of the race is running and you need traction for the sled push. Wear the shoes you trained in rather than a brand new pair.
Gloves are optional. Some athletes like them for the sled pull and farmers carry, while others prefer the chalk that is usually available on course. Train with whatever you plan to race in.
Stick to a light pre-race snack your stomach already knows from training. Race day is not the time to try new food, so rehearse your fuelling during prep.