OP already said that their current DHCP solution (the router) can't push multiple DNS servers. Having a good secondary can be really helpful for things like power blips, maintenance windows, and cats pulling power cables. There are a few solutions that also do ad blocking that can make good secondaries
If you already have pihole in your environment, I would just use that. DHCP is pretty light weight, so the pi should be more than capable, and you don't want to complicate your core services more than you need to
Be careful with the Intel laptop chips and make sure you understand what you're getting. My work laptop has an i7 with 12 "cores" but it's 10 of the low powered e-cores and 2 of the hyperthreaded p- cores, so for heavy applications (like compiling) it's a glorified dual core i3.
OP already said that their current DHCP solution (the router) can't push multiple DNS servers. Having a good secondary can be really helpful for things like power blips, maintenance windows, and cats pulling power cables. There are a few solutions that also do ad blocking that can make good secondaries