Links clicked by the user on the gateway currently show an error popup. (Such links could be seen in whonixcheck, logs, help files, etc.)
Link Confirm Open does not support opening links on Gateway for security reasons. Please copy the link to the Workstation and open it there. Use Tor Browser under Workstation to browse the internet.
In Qubes, we might be able to do better than that.
qvm-open-in-vm anon-whonix https://www.whonix.org
First, dom0 would show a confirmation popup.
Second, anon-whonix's open-link-confirmation would show a confirmation popup.
The following link will be opened in Tor Browser. Be careful if Tor Browser is already running as your activities might get linked. file:///tmp/sys-whonix/tmp.yoMl6S7xV0 Continue?
It also seems a bit weird to default to opening inside anon-whonix. (I can easily make that configurable through /etc/open_link_confirm.d.) But I don't know how the gateway could figure out any reasonable, or running, or anon-link, or existing whonix-gw based AppVMs. However, it should be good enough, because many users will have anon-whonix thanks to Qubes management stack.