Larby said:
PS. I’m not talking about a crankset freewheel.
FWIW, the crankset freewheels I am aware of use the same threading as the ones for the rear wheel, so if available with the correct threading version would serve the same purpose, as long as they support the sprocket size you wish to use (since they probably will not have teeth on them, but rather a bolt-on-flange with a BCD to match some chainring / sprocket BCD).
Regarding sources, this page
https://www.google.com/search?q=left-hand+freewheel
finds a number of places with info on them, and a few in-stock sources of different types. Whether any of them will ship to your location, I don't know--that you'd need to check. I also don't know that they are the specific thread pitch or diameter that you want (since that's not specified in your posts, but since your shaft is a fairly small diameter you could probably use *any* of them, just need to buy or make the right threaded adapter for your shaft).
Some example in-stock source links from the search:
https://www.benscycle.com/acs-southpaw-freewheel---16t--gun-metal--for-left-hand-drive-single-speed-freewheel-acs-k2725-fw1245/p
https://tncscooters.com/index.php?route=product/product&product_id=391
https://www.amazon.com/ACS-Southpaw-Freewheel-Drive-Metal/dp/B00X057BPY
https://www.ebay.com/itm/263877848884
https://www.walmart.com/ip/ACS-Southpaw-Freewheel-Left-Hand-Drive-20t-3-32-Gun-Metal/51743785
If you're really desperate, you can make a lefthand *jackshaft* freehub out of a righthand version, but it wouldn't mount directly to the motor.
http://www.recumbents.com/mars/pages/proj/tetz/VFS/projtetzVFS02lefthanddrive.html
As an alternative, since you have an output shaft that needs an adapter to mount a threaded freewheel anyway, you could just use / make one with a lip on the outboard (left) side, and then a standard righthand threaded version would work fine, as it would just tighten up against the lip exactly like it would against a rear hub, etc. Atomic Zombie used to sell this one
and Staton sells ones like this
https://www.staton-inc.com/store/index.php?p=product&id=876
Staton also has LH freewheels on this page of various types of freewheels
https://www.staton-inc.com/store/index.php?p=catalog&parent=106&pg=1
and they also make a lockring for RH threaded FWs to do the same thing as the lip described above
https://www.staton-inc.com/store/index.php?p=product&id=1305
If you have a lathe you could turn this down to 1.375" and thread it to match whatever FW you want to use
Weldahub W 5/8" ID Round OD is 1.625"
https://www.staton-inc.com/store/index.php?p=product&id=2059