If it can be sold on Ebay it will pretty much be your only means or somehow finding a player wiling to part with it elsewhere. Bethesda is unlikely to sell it otherwise since it is a promotion to encourage people to come to their presentation at the convention.
For completeness: a copy of the coin was included in the care package with a signed copy of Summerset. There may have been other sources. Additionally, the coin might be given out again at future events, though I don't know.
Yes, it is not fair, but sadly that's the way it is! Conventions are generally held in North America because that's where the game devs are based, so it's much easier for them to attend their own gaming conventions. Only very rarely are conventions held in Europe / Australia / somewhere else so fans who live in those countries continually miss out on these special convention promotions.
We all know that there are those who make a business out of attending conventions purely to "collect" these special, limited items and then sell them on Ebay for ridiculous amounts! Of course it would be great if game companies like ZOS were to make these items available for sale outside North America, but that's more wishfull thinking than a possibility!
Note that it's not just the "French community have nothing like that" but everywhere outside of North America that has nothing like that!
Elder Scrolls gaming since November 2002 (Morrowind, Oblivion, Skyrim & Elder Scrolls Online)
OP.... Maybe you could post a picture of your Elder Scrolls collection. It is possible (not likely) that someone from ZOS might see this thread and decide to send a coin to you to add to your collection... or maybe another player that is going to the convention?
I personally think the coin is cool but I am not a collector of such things and I am pretty sure should I ever get one I would end up losing it .