I have not had much luck finding a definitive answer.

VPN router plus a VPN client on PC?

I contacted my VPN provider about this and was told you can't do that but not much help understanding why not.

I can see if you use same VPN service they may encounter issues connecting two of their own IP addresses to create a double vpn. ( Some VPN services like Nord offer double VPN as well as VPN over Onion )

I have a security blog, www.4yourprivacy.com and want to investigate this topic for an article there.

If I were to install VPN in router from provider "A" then subscribe to provider "B" and install their client software on desktop (and smart phones perhaps) would these two daisy chain in effect sending traffic across both VPN service for extra protection?

One thought is that if one did keep a log file it could only show a connection from or to the other VPN's IP address.

Thanks in advance for any insight.