This is a tricky one and AFAIK not generally solvable…
As soon as there are more than 1 credential authenticator as alternatives, the order in the flow is ignored, but the order of the credentials in the current user is being used. If you get the passkey alternative first, most probably in your user the passkey credential is the first one. Another user with a different order of credentials has another first option.
You can drag’n’drop the order of the credentials of a user. Only an admin can do this for single users, no bulk operation. Additionally, the user itself is not able to change the order…
It is, what it is. It was a design decision. I don’t like it either.