A single hose, were you to make one, would have to be bespoke, as no manufacturer makes a hose with a metric fitting at one end and imperial at the other!
But in any case, a single hose is not really workable as there is too much suspension travel and steering movement to make such a single hose practical, it'd be bound to rub or foul somewhere under some extreme of operation. Modern cars that use such convoluted hoses nearly always have a grommeted support bracket halfway through their length.
A different approach is to relocate the body side hose end bracket for the flexi a lot further back, aft of the axle centreline by the same amount it is now forward of that line and then fit a shorter hose direct to the caliper. The imperial/metric mismatch still applies, but a full metric hose could be used, as a bespoke hard line TO the flexi would now be needed and it'd be just as easy to make THIS hard line metric at the flexi end.
As most people know, I have had hoses made that use the Standard flexi in the standard position and merely bridge the gap previuosly filled by a short hard line between caliper and flexi. These have been through several years of development and modification to end up with a handed pair that have a 90 degree angled hard end at both ends and a handed 120 degree offset that is opposite for each side so it's not twisted in service. This complication to avoid the above mentioned chafing created by a straight union end in the caliper, the curve of the hose fouls the top wishbone on or near 1 full lock each side, made worse if the car is lowered, which alters the top wishbone angle.
These are the hoses i've had made.
The bad news is, i'm out of stock! It's been more than 2 years since I last ordered any, they are getting increasingly expensive (isn't everything?) and the guy who makes them for me is in his eighties!
HOWEVER, I still have my patterns and i've had enough enquiries in the last few weeks to make it worth ordering several more sets and even find an alternative supplier if necessary (the guy might have retired by now, or worse)
As a rough guide, the last batch sold at £65 a pair (including UK postage) but time and suppliers will only make them costlier.
At the moment all I can say is leave it with me for a couple of days and i'll see what I can come up with and report back here.
Steve