Strictly speaking, one couldn't do it properly, rendering the pages as actual text for TUIs rather than graphically for GUIs, until Unicode version 13 came along, which included the necessary block graphics characters and which was only 5 years ago.
And even then one needs modern fonts like Viznut's Unscii or GNU Unifont or which cover the necessary code points (or one of the terminal emulators that algorithmically constructs block and line characters, and has been updated for Unicode 13).
Even if it couldn't be perfectly replicated, I'm sure it could've been done in some way before - after all, it's almost 20 years since someone set up a telnet service which broadcast football World Cup games as converted ascii "video" generated live from the TV broadcasts! https://www.freshandnew.org/2006/06/watch-the-world-cup-in-a...
(And I actually remember it being surprisingly watchable, you could follow what was happening in the game even though you couldn't judge stuff like players' ball control or anything like that.)
Ah, ok, you meant 'terminal'. There are ceefax clients for terminal too.
But you need to change the font for XTerms.
With framebuffers under Linux/BSD you might be able to do the same, but
you would need to convert the fonts first and map the chars.
Of course I have. It's nothing impressive and far from a 100% clone of the CEEFAX page. But its a start if someone wanted to take it further. I was more interested in trying out ratatui with Gemini.
You need some U.K.-specific knowledge, which is that CEEFAX went off air in 2012. If you see a screenshot of genuine CEEFAX (not one of the several modern things that pretend to be teletext) it will be from before 2012, possibly from long before as it was a service embedded in analogue PAL broadcasts that was capturable as page text (with all of the control characters) by BBC Micro users (who had bought the Acorn "Teletext Adapter") as long ago as the early 1980s.
I'm surprised no one's made a CEEFAX replica for the terminal yet [0]. Their weather page is pretty iconic [1].
[0] There are CEEFAX Emulators online that pull from the BBC RSS feeds to do this.
[1] https://teletextart.co.uk/wp-content/uploads/2016/05/weather...