There is a lot of info to google about seo.hidden metafield if you need details.
This would not require any coding.
Make sure product does not get included in any automatic collections.
You may also want to redirect people who did not have a proper link to the full-priced product – that would require some code. DM me here if you like
You can also approach it differently:
- create a discount for this product
- use link which will automatically apply this discount to share via ads
Check this How to insert discount code into URL so discount is auto-applied to all prices