I’ve been using No-IP free plan for years without issues. Inputted the credentials to my routers DDNS client and then basically forgot about it. Free users need to confirm their account once a month via email but that’s just one click.
If your domain registrar happens to have an API to update DNS entries, you could implement DDNS yourself by writing a simple automated script to check the external IP (e.g. via ipify.org) and if it’s changed from the last check then call the API to update the DNS entries.
Sure. I’m not recommending anything, just stating what has worked for me. For simple use cases, I think most of the DDNS services are pretty much the same anyway and it’s easy to switch to an another one if one stops working for some reason.