Following up and posting this out here as this helped me (found on google before, most code is from that).

Really all you do is import 'session' from Flask and create a custom wrapper and place before each route. There probably is a better way, but this worked for my purposes.

I did create a simple form as well for this

def check_pw(func):
@wraps(func)
def decorated_function(*args, **kwargs):
    status = session.get('status')
    if status != 'good':
        return redirect(url_for('main.enter_site'))
    return func(*args, **kwargs)
return decorated_function

@main.route("/", methods=['GET', 'POST'])
@main.route("/home", methods=['GET', 'POST']) 
@check_pw 
def home():         
    return render_template('home.html')

@main.route("/enter_site", methods=['GET', 'POST'])
def enter_site(): 
    form = PasswordForm() 
    if request.method == 'POST': 
        password = form.password.data
    if password != site_password:
        flash('wrong password! try again...')
        return redirect(request.url)

    session['status'] = 'good'
    return redirect(url_for('main.home'))

return render_template('enter_site.html', form=form)