The seller asks for an advance payment. Is that normal
In shortSometimes yes, but it moves the whole risk onto you, and the decision has to be deliberate.
An advance payment means you have performed your side and the other side has not. From there everything depends on their willingness to continue, and no mechanism on your side changes that.
If an advance is unavoidable, its size and route are chosen so that at least one path stays open for you: a card with a dispute route under the scheme rules, or a platform that holds the money until receipt is confirmed.