The idea of succinctly giving more information to the people using our applications is great. Personally I like the design you’ve come up with. But there are a few things you might not have thought of.
Accessibility: People with eyesight deficiencies are going to find it very hard to tell those icons apart. In addition on some mobile devices, those icons would be very small and hard to tell apart. If people are using screen readers, you could get the link to read differently depending on how it would open so that could work (I think).
Best UX: The concept of building the ‘best’ UX into the browser is interesting. The ‘best’ UX is very dependent on context. I can image designs where adding the icons to the tops of lines could be very jarring and you deliberately wouldn’t want them. For example if you think about line spacing, the position of you icon gives a minimum viable line spacing to use and could interfere with a reader's eye passage on the line above. Alternatively think of a bullet point list of links, I can image the icon being hard to tap as it would be very close to the link above it.
It would be really interesting to see some real websites with this applied.
Having said all that improving the defaults you get in the browser to not be based in the last century is probably a step in the right direction.
I also agree with Sidiali’s response, use a default rather than three icons.