What, exactly, makes it poor? Be specific.

I will be very specific about why it is poor. The specific reason is my home network is not the Advanced Research Projects Agency.

having two levels, for one. "arpa" not being remotely memorably to non-technical people, for another.

- WTF is arpa? (in reality, I know, but there are better names than an obscure reference to internet prehistory)

- it is a second-level domain, why?

- 9 characters (home.arpa) is a lot

I kind of understand the motivation, it is a "technical" domain since it doesn't represent something in the global DNS registry, so it gets the .arpa TLD. However, that's reasoning that it out of touch from normal users. Normal users don't want to be exposed to the technicalities of DNS when they enter something in the address bar, and "myserver.lan" is more meaningful than "myserver.home.arpa", and giving meaningful names is the whole point of DNS.

The character count. lan is 3 char, home.arpa is 9. Subjectively, tt is also aesthetically unappealing.

I can't fucking _wait_ to type bender.home.arpa instead of bender.lan. Hyped.

Then use search domain and let your DHCP and DHCP6 server hand that out to clients.

or we could just not publicly delegate a defacto private space?

Search domain is handy but it's ambiguous.