If I understand correctIy, you are aiming for filtering public DNS queries while wanting to preserve your existing local hostname resolution.
Pi-hole does support this, and there would be two ways to address it.
a) configure Pi-hole as your router's upstream DNS server
Without Pi-hole, most routers will accept DNS queries from local clients, provide local hostnames as known, and forward any remaining DNS requests to its upstream DNS servers as provided by your ISP.
By replacing your router's upstream DNS servers with Pi-hole (and Pi-hole only), your router and clients behave just the same as before, while Pi-hole is providing it's filtering capabilities.
In this scenario, since only your router is asking Pi-hole for DNS resolution, Pi-hole will see all DNS traffic as originating from your router (apart from its own queries). You do not have the ability to attribute DNS queries to a certain device in Pi-hole's statistics.
b) distribute Pi-hole as local DNS server via your router's DHCP with respective configuration options
When successfully distributing Pi-hole this way, your clients will ask Pi-hole (instead of your router) for DNS resolution. Since Pi-hole is oblivious of local hostnames as assigned by your router, it will either come back with an empty answer straight away, or it will forward those queries to its upstream servers, which also would not know any of your private names.
There are two ways to overcome this:
b.1) use your router as Pi-hole's solitary upstream DNS server
If you do this, you also need to uncheck Never forward reverse lookups for private IP ranges on Pi-hole's Settings | DNS panel.
Depending on how your router handles names, you may also uncheck Never forward non-FQDNs.
b.2) enable Conditional Forwarding
In both cases, you must not configure your router to use Pi-hole as upstream DNS - that would close a DNS loop, likely incapaciting DNS.
In this scenario, Pi-hole's statistics will show individual clients (as distinguished by a DNS request's IP address) with their respective local names.