Riven(2024) Opening and Ending cutscenes together at last.

It starts with clicking on the Riven linking book while reading. You can then hit ESC while loading into Riven and get a brief menu that allows you to save. Since it's a save and not an autosave it wont be overwritten, and you can do things with it.
The trick is avoiding loading near the cage, since it locks you in place and plays the Cho cutscene. A rough outline of how to get around this is below.
Continue game normally.
Save near Maglev
Use "Fall Anywhere" glitch to fall through the ground on the save just before Cho.
Fall until subtitles appear, and crash game.
Load the autosave, and save it.
Load maglev save and use it to skywalk on the save you just made.
You can now escape the cage by holding (I think back and right) as that save is loading.
Thanks to the skywalking you can skywalk over to Jungle Island, and save near-ish the animal puzzle.
Save/Load.
Solve puzzle, go to Tay.
Close game.
Load Tay save, now without skywalking.
Get Catherine's Journal (you have the trap book)
Leave Tay
Use Minecart to fling to between Temple and Boiler.
Read and Stop reading to teleport into the gold dome.
Float around the outside of the turny room to open the gate blocking
on the gold dome side.
Float back to the gold dome.
Save, Exit Game, Load gold dome.
You can now finally power the Telescope.
Save after entering Telescope code.
Load save.
Cho cutscene is now active.
Activate end cutscene.