[Answered ]-Is it possible to add more fields to admin/auth/user?

are not being saved in admin/auth/user

Indeed, these are safed on the UserProfile model.

You thus can make a ModelAdmin for this:

# app_name/admin.py

from django.contrib import admin
from app_name.models import UserProfile


@admin.register(UserProfile)
class AuthorAdmin(admin.ModelAdmin):
    list_display = ('first_name', 'last_name', 'username', 'email', 'pfp', 'bio')

Then the details can be seen in the admin/app_name/userprofile section.

Create a custom user model by inheriting the AbstractUser and adding extra fields needed. After that, register that custom user model by assigning it to AUTH_USER_MODEL.

Check here for detailed implementation.