I am about 80% certain that in the time it took you to write this comment you could have bought a domain name, used the registrar's web-gui to input your now static IP addresses, and had a perfectly functioning DNS setup for your home.
I have a domain name. Setting up subdomains and binding it to addresses is non-trivial.
I have to figure out all the business of anames and MX records and how to set up a subdomain.
And considering that routers issue ipv4 addresses automatically, offer user-friendly GUIs for binding addresses to devices and forwarding ports, it's not really comparable is it?
You are not comparing apples to apples here. You’re talking about setting up MX records vs memorizing an IPv4 address. There is no way that pxtl@random-IPv4-address is how you’re handling your email.
If you can run a server securely on the public internet, you can set up a domain name. To pretend otherwise is a little absurd. Frankly if you can’t set up a domain properly in DNS, you probably can’t successfully manage to forward a port to your server anyway.
I am about 80% certain that in the time it took you to write this comment you could have bought a domain name, used the registrar's web-gui to input your now static IP addresses, and had a perfectly functioning DNS setup for your home.
Or, if the free DDNS is the most important to you, OpenWRT appears to natively support quite an extensive list: https://openwrt.org/docs/guide-user/services/ddns/client