To be blunt, I would no longer use steel conduit as the CPC, because
1) it must be maintained 2) too many 5-day people use 15mA EFLI
testers without understanding their limitations (namely that what
passes a 15mA test may not pass a 25A test).

Plastic conduit is fine with 6491X, FTE is an exercise in frustration
if you are a suitable masochist (6242YH is bad, 6242BH with its
tougher sheath would be friggin hilarious around a few bends).

You can buy cut lengths of 6491X online. TradingDepot, perhaps
AlertElectrical, Gil-Lec, TLC for gr/ye, a few others.

The problem with stocking cut lengths of 6491X is volume & having
sufficient reels set up to meet demands without wastage. Would be
better if they sold say 10m of large & 25m of small multiples which
would not be a bad idea (enough for a shed or garage basically which
is where 6491X does get used domestically).

If there is no real requirement to use conduit, I would use oval.

Where conduit & flexible conduit can come into its own - even with
6491X is for kitchens, particularly with stud walling. Very easy to
create an unpopulated network of conduit ready for any future changes
so making kitchen refurbs a lot simpler (remember tile trim for on
worktop so apes don't destroy the tiling). You could extend it to
network drops and throughout the house - even if not used the oval/
conduit saves plaster :-) Makes it a lot easier than "damn, I wished
I'd..." having decorated vs simply having to measure & cut out a box
over pre-existing oval/conduit.