You can set the minimum extrusion width to a small value (20-25%) for better fill. You could also use classic mode with gap fill. You can use ironing for both to improve the results.

Does your slicer have Arachne slicing mode? It will use variable extrusion width which will help to prevent most of those gaps.

Use the recommemded parameters: https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-argon2-04#page-11

Also consider WebauthN/Passkeys. They are much less ressource intensive on the server but useless to an attacker when the database is leaked and as such don’t rely on slowing down the crypto operations.