Since you run already OpenWrt, you can check out https://openwrt.org/docs/guide-user/services/ddns/client
There is a list on this page of compatible services. If you don't want to use one more service (DNS), you can use a domain registrar with an API (like porkbun) and find online tools that work with that.
Be aware of the risks of hosting your websites publicly from home, make sure to run them in very isolated environments. Having your VPS compromised is bad, but having your home network compromised is much worse!
Yeah, what I mean is that it's useless using ports like 2222, that's like the unofficial SSH port! Bots are generally harmless (once you move to key auth), and you get functional the same result with the automatic IP ban on failed auth, minus the bother to change client configurations to your custom port. Anyway, if someone does want cleaner logs, changing port works :)