Any DNS provider is good if they offer an API that lets you use PUT to modify DNS records. You can make a small bash script and crontab it. I also used DuckDNS for a while, and it worked fine.

It has the Firefox extension “Wallabagger”, open-source and all. You just have to create a token in Wallabag, link it, and then it works like a charm. Doesn’t work exactly like OP wants though.

They should also add support for Unified push. More apps need to embrace it! Currently there are no notifications at all.

It’s just 2 programmers from what I’m aware. When you go to donate they say that the goal is 5000€/month, but they usually fall drastically short of that.