I mean, would people who play the PTCGO be interested in free packs? Yes, absolutely. Aside from the codes, there definitely exists a public for unboxing and pack opening videos.
Now, if you intend on advertising this in this forum you'll run into a different type of issue. The standing of the administration with regards to external sites is rather strict. As you can see from you post, you couldn't type YT because it got censored with a bunch of asterisks.You can just type "YT" like I did, but if you do that for anything other than making a passing reference to it (as in, if you tried to continuously advertise your channel), these post would in all likeliness get deleted. My guess is that this has to do with the fact that the target audience of the game is mainly children, so they're afraid to allow links to sites where they have zero control over the content that is displayed. It's probably the same reason as to why the curse filter is so strong too.
I think (although I cannot say this with certainty) you might have better luck advertising yourself on other Pokemon related sites like the PTCGO's Reddt, and Pokebeach (do make sure to ask about the rules there before advertising your channel; I do not actively participate in either of those so I don't know the rules myself). Other that, you could try finding personal contacts with some interest in this and try to get your channel advertised by word of mouth. If you know any local leagues or groups of people in your area that play the Pokemon TCG, that might be a good starting place.
One last thing I could suggest, is that you make more Pokemon TCG related content, such as making and testing decks, while making periodic giveaways at the end of your videos. It's a very commonly used strategy, but it works. Now, do keep in mind you have a lot of competition in that field (there are a lot of known YTbers who make this kind of content), but I think it's worth a try anyways.
Good luck buddy, I hope you can make your channel grow.