Laptops are quite capable of running Hauptwerk Advanced. The main limitation would be the RAM capacity, as this would determine which sample sets could reasonably be loaded, and to what extent.
I have been using a MacBook Pro 15-inch (2012 model) for Hauptwerk Advanced ever since I purchased it. I use this as my portable HW computer for work as a music teacher. I only need 2-channel stereo, and Mac audio is excellent, so I don't need to add an external audio interface.
I have carried out several enhancements to this laptop. It now has a 1 TB internal SSD, a 5 GB external drive (which contains the bulk of the Hauptwerk files) and 16 GB of RAM which is the machine's maximum. For my purposes, this is fine.
If you are looking for 32 or 64 GB that might be an issue, but I'm not up to date on what the latest laptops can do.
If you go for a PC laptop, or if you want multiple channels on a Mac, you'll need an external audio interface. If 2-channel stereo is enough, then a Mac alone should do the job.
Andrew