I have a USE Shokpost on my bikepacking hardtail. This is a durable and rebuildable product, as mine has been on several bikes since I purchased it in 1993! There is also the “Thudbuster” type of shock post, with Suntour selling the SP12-NCX, sold on Amazon. USE currently has the Vybe model on their UK website.
The last option is to look for a saddle with an elastomer isolation system, either as padding or as part of the rail. This will offer only minimal protection.