You can add a Facebook Pixel to your website using Google Tag Manager
Step 1 - Link your Google Tag Manager account to your VIA software
Create a new GTM account at http://tagmanager.google.com , or use an existing account that you’ve already setup for your business
Login to your GTM account and copy your Google Tag Manager Container ID
Login to VIA
Go to Settings > Website > Onyx_Config
Paste your Google Tag Manager Container ID into the Google Tag Manager Code field
Click Save
Step 2 - Add your Facebook Pixel to Google Tag Manager
The guide below shows you how to add you Facebook Pixel to your website using Google Tag Manager
https://www.facebook.com/business/help/1021909254506499 quickly and easily. Once you have you created your Facebook Pixel code
In the left hand menu go to Settings > Configuration > Third Party > Meta
Paste your Facebook Pixel ID into the Pixel Code field. This is will be a 10 or 11 digit numeric code. guidance on locating this can be found here https://support.shareaholic.com/hc/en-us/articles/360000428223-How-do-I-find-my-Facebook-Pixel-ID-
Your changes will automatically be saved