It seems the 440 wheels are now available separately (at least in India) from this company:
throttleandthump.com
with a caveat as it seems (quoted from reddit)
HIMALAYAN 411 ALLOYS ORIGINAL - SCRAM 411 COMPATIBLE TOO - Throttle&thump
himalayan 411 alloys, scram 411 alloys, himalayan original alloys, himalayan alloy setup, original alloys for himalayan 411, himalayan tubeless wheels
throttleandthump.com
with a caveat as it seems (quoted from reddit)
For fitting the front alloy wheel, you'll need a spacer slightly larger than the current front spacer. The speedometer cable will need to be repositioned under the Himalayan's instrument cluster. There's also another spacer in the the speedometer in front tyre that needs to be cut down by about half to fit perfectly with the front wheel.
For the rear alloy wheel, the fitment is direct — it fits straight onto the rear without any modifications.