You VPN into Canada and then sign onto another VPN from there? Would that work?

Hell, depending on how the law is written and how clever the lawyers are, the VPN can ship you out to Canada, then connect you back to the network via an authentication token that verifies you are a member of the service without verifying your country of origin.

Why would a Canadian VPN server obey US block lists?

I don't know if you're familiar with how VPNs work, but it's basically like a computer in the other country is sharing its internet connection with you.

So let's imagine that things are reversed, and you're a VPN provider in the United States and you're sharing your internet connection with some computers in another country, like Saudi Arabia, for example.

And just to be clear, you conduct no business in Saudi Arabia. You're just sharing your internet connection with people from there. You don't have any associates in Saudi Arabia, and you have no intention of ever going to Saudi Arabia.

And let's say that Saudi Arabia passed a law that said VPN providers had to block some kind of content, like maybe banning all access to content about your favorite band.

How is this going to affect the VPN service you provide to the other computers?

Wrong question these days.