King meter are usually only OEM supplied as with your bike, it will be programmed as a pair with the main controller so not just a simple buy and fit option.
A bike shop or ebike shop won't touch it with the proverbial barge pole not because it is not an ebike they sell but simply because they won't have a clue.
For instance the King meter is programmed to XX brand of controller and could also be programmed to another brand of controller YY. Both King meters although they look the same and have the same display commands, it is the software/firmware that will differ so one brand will not be compatible with the other brand. King meter only supply the displays to the brands to sell with their kits, it is the brands that programme them and not King meter.
Tbh and as with a lot of after market OEM bikes the only answer really is to spend about £100 and find someone to retrofit a Kenteng (KT) controller and lcd display , these items are freely available on the market and will give a better set up then the one originally supplied. KT supply to any one wether OEM, third party retailer to the end user, these are all programmed by KT so in nearly all cases one can simply buy a KT to fit and it will work.