How can I get a Canadian non-circulating coin?

Can I reserve or buy one on the official website of the Canadian Royal Mint?

Probably not a decade old coin, only the new stuff they churn out by the hundreds every year.

Don't know what sites are available behind the great fire wall but on ebay and other similar auction websites you can probably find some for offer.

You can look at the shop on mint.ca. However, I do not know if they ship coins abroad if at all

I believe the RCM ships only to Canada and the USA. These seem to be the only two options on their website, but they provide names of sellers / distributors appointed by them in the rest of the world.

Several years ago, I ordered for a British Numista member a birthday set which I forwarded to him since he couldn't obtain it directly from the Mint's online store.

You would have better success by contacting a Canadian Coin Seller.  Send me a message in Numista and I can refer to you to my local coin shop…

You may be able to find something here. https://www.colonialacres.com/collections/royal-canadian-mint