Python Postgres pull as byte object vs str

I'm doing a basic Python Flask application with a Postgres database using psycopg2. I'm having trouble setting up the user registration password hash as it appears I'm working with a string vs byte type. Fundalmentally, I'll get this error when doing the password re-hash on the login (after registration and initial hash)

hash_value = hashlib.pbkdf2_hmac(
             
# TypeError: a bytes-like object is required, not 'str'

Here is the relevant table setup:

CREATE TABLE IF NOT EXISTS myschema.mytable
(
    --Unrelated fields...
    password_hash character varying(500) COLLATE pg_catalog."default" NOT NULL,
    salt character varying(100) COLLATE pg_catalog."default" NOT NULL,
    --More unrelated fields...
)

This is how I'm inserting the data:

# Code above that is setting up a DB utility, configs, etc...
# Hash the password
salt = os.urandom(16)
iterations = 100000
hash_value = hashlib.pbkdf2_hmac(
    'sha256',
    password.encode('utf-8') + app_config['PEPPER'].encode('utf-8'),
    salt,
    iterations
)

password_hash = salt + hash_value

# Redacted extra fields
query = "INSERT INTO mytable (password_hash, salt) VALUES (%s, %s);"
params = (password_hash, salt)

# This kicks off the standard cursor execute, etc...
db.query(query, params)

And for the retrieval:

# Code above that is setting up a DB utility, configs, etc...
query = "SELECT password_hash, salt FROM mytable WHERE email = %s;"
params = (email,)

users = db.query(query, params)
db.close()

# No user found
if not users:
    return False

db_password_hash, db_salt = users[0]

iterations = 100000
hash_value = hashlib.pbkdf2_hmac( # This will be the spot that throws the exception as it expects bytes for 
    'sha256',
    password.encode('utf-8') + app_config['PEPPER'].encode('utf-8'),
    db_salt,
    iterations
)

# Then commence validation logic, etc...

I have tried using bytes(db_salt, 'utf-8') as it's really throwing the error on the salt field. However, this will not yield a successful rehash. I'll take recommendations - this is new development so if I need to do a postgres binary type I can do that too- whatever option makes sense here.

Thanks!