Question - if your domain registrar has an API to update your A/AAAA records, and your router (or other home server) lets you easily update those records via the API when your public IP changes, is there a benefit to using freedns or any other DDNS service? It seems like you don't really need them if you own a domain.

Yes, it's why I stopped using DuckDNS and decided to buy my own domain. I used Porkbun and got a cheap one (~$15/year?). It was super easy, and DNS results are lightning fast now; no timeouts/errors/etc. like when I was using DuckDNS.

My router supports Porkbun for DDNS; it handles updating the A/AAAA records for my domain when my IP changes, but if your router doesn't have that option, I'm sure there's a script you could run on a PC or Raspberry Pi, etc. to handle that for you.

I honestly don't know why I didn't do this sooner! I've changed DDNS providers a few times over the years and it's always a pain to update everything that references the old names. It's great having peace of mind knowing that I own the domain now and won't have to change again (even if I wanted to leave Porkbun, I could just transfer the domain registration to any number of good alternatives and not have to change my domain name).