As you are using NordVPN: Yes.
If you use a VPN service provider, a third party would only be able to observe that you send and receive encrypted traffic to your VPN provider's servers.
If you exempt DNS from that traffic, a third party would be able to observe which domains you resolve - something you absolutely want to avoid when connecting to public networks.
But whether you use encryption or not:
The public DNS resolver processing your DNS requests has your DNS history.
In case of a VPN forcefully redirecting DNS to your VPN provider's DNS servers, that would be your VPN provider.
The relevant question is:
Does it defeat your purpose?
What are your preferences with regards to confidentiality, authenticity, integrity and privacy of your DNS traffic?
If you use unbound as a validating recursive resolver, no public DNS resolver has your DNS history, and DNSSEC validation guarantees authenticity and integrity of DNS replies of authoritative servers supporting DNSSEC - but your DNS requests are not confidential, as third parties can observe your DNS traffic. Confidentiality is particularly relevant when connecting to public networks, but not a major concern in your home network.
If you use a DoH/DoT forwarder instead, DNS traffic would be encrypted, so third parties can't observe your DNS traffic - but you'll entrust your chosen public DoH/DoT DNS resolver's with your DNS history, and by itself, DoT/DoH cannot check for authenticity and integrity of DNS replies (DNS root servers currently do not support encryption).
However, when using a VPN service provider, your entire traffic (including DNS) would already be encrypted, i.e. you are already protected against third party eavesdropping.
DoH/DoT would be useful to provide confidentiality of DNS requests for roaming equipment like a smartphone or laptop when connected to public networks, like a cafe's, hotel's or airport's wifi.
In a similar fashion, using NordVPN on a laptop would provide confidentiality of all traffic, not just DNS.
For your own home network with secured wifi access, running unbound as a validating recursive resolver would check authenticity and integrity of DNS replies, without you having to entrust a public DNS resolver with your DNS history.
(I personally do not use DoT/DoH - instead, I run a VPN server in my home network, so my roaming devices send their DNS traffic via an encrypted connection to my Pi-hole / unbound at home.)
Your choice comes down to what you want to achieve.
Beyond a VPN service providers obvious benefit of offering confidentiality in public networks, you may have opted to use NordVPN for geolocating purposes, or for an extra bit of online privacy.
Whatever your reason for routing your home network's traffic through NordVPN, you should be willing to entrust NordVPN with your public DNS history.
If you do that, you may remove unbound from your home network and point Pi-hole to NordVPN's DNS servers, with your router enforcing NordVPN's dial out profile for all connections.
If you don't, you could decide to just use NordVPN on your roaming devices when not at home, while keeping unbound for your home network.