diagnoses_curtsy that's weird. If I open a pdf with the link, I can select the link just like any other text, but in addition, when selected, I see my default browser as a first action in a context menu, I assume as the text is recognised to be a link.
What's convenient, is that when I tap and hold on a long link (with subpages), then the whole link is selected automatically and not the single word part of it, so kudos to gos pdf viewer devs for that.
The only thing that doesn't have a workaround, is inability to follow internal PDF links to other parts of the same document.