Shortcat is my favorite of these sorts of apps. I just wish there was a way to make all of them faster. The delay between requesting the link hints and then actually displaying on screen is painful enough that I haven’t been able to incorporate it into my workflow.
Most of these apps seem to tie into MacOS’s accessibility framework for the hinting, and I’m guessing the delay is being caused by waiting for and then acting on these response from that framework.
The app in the screencast is Firefox; if you run Accessibility Inspector.app and try to inspect, for instance, the "NN minutes ago" link text in your comment, this is what it looks like in Firefox [0] and this is what it looks like in Safari [1].
Firefox (and Chrome) look like giant completely opaque windows to the macOS accessibility API, the only things you can "see" to click on are the close/minimize/maximize buttons, whereas Safari exposes its entire interface and a lot of the web page to the API.
It looks like Homerow is somehow scraping a short list of apps, "Popular non-native apps such as Chrome, Firefox, Brave, Arc, Visual Studio Code, Spotify, Slack, Discord, and Obsidian are supported. I'm working on supporting more non-native apps.". I don't know how shortcat etc do it, but all of these approaches might just be slower than using the accessibility API.
