Not sure if you found the answer but here is what you need.
tee -a /etc/dnsmasq.conf << EOF
dhcp-match=set:ipxeclient,60,IPXEClient*
dhcp-match=set:bios,60,PXEClient:Arch:00000
dhcp-boot=tag:bios,netboot.xyz.kpxe,,192.168.8.1
dhcp-match=set:efi32,60,PXEClient:Arch:00002
dhcp-boot=tag:efi32,netboot.xyz.efi,,192.168.8.1
dhcp-match=set:efi32-1,60,PXEClient:Arch:00006
dhcp-boot=tag:efi32-1,netboot.xyz.efi,,192.168.8.1
dhcp-match=set:efi64,60,PXEClient:Arch:00007
dhcp-boot=tag:efi64,netboot.xyz.efi,,192.168.8.1
dhcp-match=set:efi64-1,60,PXEClient:Arch:00008
dhcp-boot=tag:efi64-1,netboot.xyz.efi,,192.168.8.1
dhcp-match=set:efi64-2,60,PXEClient:Arch:00009
dhcp-boot=tag:efi64-2,netboot.xyz.efi,,192.168.8.1
EOF
uci set dhcp.@dnsmasq[0].dhcp_match=set:bios,60,PXEClient:Arch:00000
uci set dhcp.@dnsmasq[0].dhcp_boot=tag:bios,ipxe/netboot.xyz.kpxe,,192.168.8.1
uci set dhcp.@dnsmasq[0].dhcp_match=set:efi32,60,PXEClient:Arch:00002
uci set dhcp.@dnsmasq[0].dhcp_boot=tag:efi32,ipxe/netboot.xyz.efi,,192.168.8.1
uci set dhcp.@dnsmasq[0].dhcp_match=set:efi32-1,60,PXEClient:Arch:00006
uci set dhcp.@dnsmasq[0].dhcp_boot=tag:efi32-1,ipxe/netboot.xyz.efi,,192.168.8.1
uci set dhcp.@dnsmasq[0].dhcp_match=set:efi64,60,PXEClient:Arch:00007
uci set dhcp.@dnsmasq[0].dhcp_boot=tag:efi64,ipxe/netboot.xyz.efi,,192.168.8.1
uci set dhcp.@dnsmasq[0].dhcp_match=set:efi64-1,60,PXEClient:Arch:00008
uci set dhcp.@dnsmasq[0].dhcp_boot=tag:efi64-1,ipxe/netboot.xyz.efi,,192.168.8.1
uci set dhcp.@dnsmasq[0].dhcp_match=set:efi64-2,60,PXEClient:Arch:00009
uci set dhcp.@dnsmasq[0].dhcp_boot=tag:efi64-2,ipxe/netboot.xyz.efi,,192.168.8.1
uci commit
/etc/init.d/dnsmasq restart
Change the IP to what your server is.