PBKDF2 is a key derivation function recommended by IETF in RFC 8018 as part of the PKCS series, even
though newer password hashing functions such as Argon2i are designed to address weaknesses of PBKDF2.
It could be a preferred password hash algorithm if storing passwords in a FIPS compliant way is necessary.
Usually, selecting Argon2i as hash algorithm is good to go.
PBKDF2 is not available on this system. This is very uncommon. If Argon2i and bcrypt are also not available,
you should seriously question the quality of your current hoster and reach them out to fix this as soon as possible.