Can you carve an heirloom squash just like a pumpkin?

Yes, but the thickness of the squash meat will affect what you can do with it. If the meat if too thin, it will dry out too fast.(like overnight). The one in your picture looks very carveable and it certainly has the forehead you’re looking for. Have fun.

From what I remember about those pumpkins (the blue australian ones) they are thick. These are the type we used to buy and eat in New Zealand. http://www.stickboybread.com/_blog/?attachment_id=146

Sure you can! Make sure you share a photo when you’re done!!
Edit- had to include these!

I carved one of those a few years ago, so it can definitely be done. However, it was so hard to carve, I’d never do it again! Just about killed my hands trying to get that sucker going.