If needed I think you could use a ffc extender board meant for standard (non-notched) cables.
https://www.ebay.com/itm/254991925413
The Framework keyboard cable is a 0.5mm pitch 26 pin notched ffc cable. Datasheet. You’d trim off the notches on the keyboard cable.
And get a cable of whatever lenght you need: 26-Pin 0.5mm Pitch FFC Cable, Forward Direction
You’d need an extender board & cable for the keyboard backlight connector too. It’s a 1.0mm pitch 4 pin ffc cable. Regular non-notched, so no need to trim. Connector product page.
Extender board and cable for backlight in various lenghts: 4-Pin 1mm pitch Extender, 4-Pin 1mm Pitch FFC Cable, Forward Direction
Of course, it would be easier using a purpose built extender board that doesn’t require trimming the notched part off the keyboard cable.