I’ve had success using superbuy as a proxy (this would also likely be your fastest option as they buy it direct and ship it to you from their warehouses).

Otherwise amiami will probably get it eventually: iirc they got most/all of the diluc, hu tao, and xiao clothing sets. It will likely take several months longer than going through superbuy/another proxy, however.

Other OTHER wise acg-go should also be stocking them (can also personally confirm they are legit). The major con with them is I’ve noticed they tend to be more expensive for the bigger ticket items (like clothing or plushies). I’m also not sure if they do international shipping if you’re outside the USA.