However, I am less certain about the benefits of using a third-party
VPN (NortonVPN in this case) when working from my home network. My
employer is under the impression it is not safe to work from home
without using NortonVPN.
Are there valid technical reasons to require a third-party VPN when
If your employer requires\advises it's employees to use VPN in order to access to work environment, even if it's simply accessing an admin panel to a publicly published website, then they have a valid point.
All your data going to the endpoint, pass through network\application of your network provider, and anywhere in-between it can be intercepted. Even https traffic is not safe, since simply deploying a proxy which requires download and installation of it's SSL certificate is enough to decrypt and view all the data you are exchanging with the endpoint.
Using third-party VPN solutions however may not be the best solution. They can be susceptible to the data leak, and it might be too late to discover that. Besides, there are no guarantee that third-party VPN vendors are absolutely self-conscious about the data that passes through them. It would be best for employer to use there own, internally deployed VPN solution.
In short - Using VPN for work, even from home is a must. Using third-party VPN for these purposes cannot be sufficiently justified.