What if someone else uses 192.168.0.5 for their printer too? This just seems incredibly insecure, where I'll have to keep a public record of the private addresses of my devices. Welcome to the Fishbowl.

Yes, RFC1918 addresses are ambiguous, and generally they have this problem, independent of using DNS. You should use IPv6 if you can.

But now you are running TLS, so the address conflict would just yield a cert error. (If the other guy plugged his network or printer into yours, that is)

Yes, I'm running TLS behind my NAT, where unsecured traffic should be safe. Or should we be using VPN tunnels within our private networks?

And at the same time, I've introduced an internet connection dependency and a 3rd party dependency. What happens when they decide to stop updating that cert, to save money?

You shouldn't treat a SOHO or home network, NAT or not, as secure. There are good reasons why we don't trust the network. Getting compromised is not an "if", it's a "when".

But then what about when the printer’s IP address changes because it’s dynamic?

ddns?

Or use addresses like https://192-168-1-1.hp.net (https://192-168-43-123.hp.net, https://10-20-30-40.hp.net, and so on) and a wildcard cert. No harder to document than telling people to go to http://192.168.1.1.

Though they should be more careful than to use to top-level domain as they need to include the private key in the device unless they have the devices call out to have a new certificate generated, perhaps 192-168-1-1.internaldevices.hp.net and so forth.

It would be necessary to use a different private key on each device for it to be secure, so something like 192-168-1-1.internaldevices1489420.hp.net

DNS got fixed to handle dynamic updates in the early 2000's.