From the project's site, an eBlockerOS-powered device allegedly uses ARP spoofing to hijack as the default gateway and serving as a second hop in the internal network. Behaving as an NGFW can have some benefits over just DNS filtering that services like PiHole achieve. Things the project lists it is capable of include global VPN tunneling, DNS request masking, parental controls, content blocking.

It could be technically better than just PiHole (assuming the project is legitimate), but I will argue so would a router running OpenWRT or similar. Depending on the SBC used with it, I would be concerned with network throughput performance (both Ethernet link speed limits and CPU utilization from certain services). Additionally, its configuration would mean it being a full second-hop device on the local network, which may cause its own category of issues. The main use case I could see for this project is if you're completely stuck with your ISP's router and cannot touch much about it.