I've got NordVPN and would like to watch out of market sports on YouTube TV. Is this possible?

pretty sure YouTube TV bases your market on your billing zip code. So a VPN would not change that. I think you'd have to change your billing zip code AND use the VPN to fool the app into thinking you're in another zip code.

What out of market games are you trying to watch?

YTV also very aggressively blacklists IPs from common VPN providers. There might be additional anonymizer steps you could take but VPN alone I don't think would work, or at least it doesn't in the case of my 3 VPN choices of corporate, SurfShark, and RA4WVPN.

YoutubeTV does not work for me most of the time when I have my NordVPN on.

In my experience YTV travels with me which is both kinda cool but also annoying. My local channels change according to what city I am currently in. I think the gotcha here is that the device must login from the billing / home zip at least once per x days (I think x is either 30 or 60).

This is a big reason I probably won't switch from Directv Stream. Using the Nord vpn app on my fire stick, I bring my channels with me on all my trips and never have to watch the stupid local sports broadcasts. It doesn't work on my my computer or iPad or iPhone though. Location services on those devices tell the app youre trying to pull a fast one.

YouTube is pretty good about spotting VPNs... The CBS and Fox apps aren't as good at it. I haven't tried it this year but in the past I had luck authorizing the CBS and Fox apps then connecting to the VPN and getting local channels in those markets.

Currently watching FuboTV with Express VPN for the Aggie game and I am on the other side of the planet from home. Granted im switching from FubtoTV to SlingTV for now to get me through the world series however I can also confirm Express VPN works for SlingTV.

Instead of a VPN, try a proxy. I use this service, https://www.homingsystems.com/ it runs a proxy through residential connections so services like YTV have a hard time noticing. You can even use that service to setup a proxy that runs through your home network, so it literally always looks like you're there.