You can get benefits on a 3rd party booking. I use Hotels.com when i’m staying in places where there are no Hiltons. When it comes to redeeming the free night, it will usually be at a Hilton.

I make the booking, then call the hotel and ask them to add my HH number to the booking.

I’ve sometimes had upgrades, always had free breakfast and lounge access. Sometimes the booking even appears in the app.

Definately no points earning though.