Nice read. Although I much prefer the first solution, the hotfix of adding extra padding to the bottom. UX-wise, not just because it is simpler.

On large screens I prefer to not read texts at the bottom (I always scroll things enough so I am looking at them at the middle or top of the screen). Also, the positioning of the heading relatively to the screen is always the same on every scroll.

While I usually detest giant footers, this is one use-case they lend benefit to, without causing a large empty space (which some people would then want to fill with an image). I agree from a UX perspective that I prefer when sites act the way I expect them to, and not try to do novel calculations of stuff (minus usability stuff like the ‘dead zone’ dropdown menu polygon calculation). On most pages, I expect a reading section to start when I scroll past a heading, and I prefer anchors to deliver the heading at the top of my viewport.