They support oscilloscope cards, except when they don't. Those are the 16530-16534a boards. Specifically, the earlier scope boards 16530-16532a have been reported to not show a trace over X for an unknown reason. I will investigate that in the near future. You will want the 16533a or 16534a oscilloscope boards. Alternatively, you can simply purchase the integrated oscilloscope versions of these analyzers.
You'll notice the 1670G model in the article has the 2ch scope built in. That scope works over X11.
This a deep rabbit hole, but my 16500B from 1992 came with a 102-channel logic analyzer and a 2ch 250MHz 1gsa oscilloscope. There are many other interesting boards it can support and I am acquiring them as opportunity presents itself. It cost me $150 including shipping. :)
Here's a good starting point into these machines. https://youtu.be/6w5w3ezpVHE?si=BfsiazkXvHK-L1MV
If you want your mind blown, consider that the 16500A came with a color touch screen in 1988 (I checked HP archives) and it could already be configured for X11 networking with the appropriate add-in card. There's also Windows software to operate these systems over a modem. The blank mainframe cost $7200.