Sorry about the HOB thought, I lose track of which post I've read---or lose my mind occasionally !
Yes, I would think that filter might be an easy, cheaper way to get both a pump and the canister to act as a reactor. The idea is the same and as long as the water is not going through so fast that bubbles that are still large enough to see get pushed down and out into the tank, it should work as a reactor and then if you want to change up and have a filter instead, it might be pretty simple to just add a bolt and some silicone in the tubing hole to seal it. I do like to keep the options open as I do change my mind.
One point that I do like is the way Grigg's did a bit harder work to pull the tubing through an undersized hole and let it come out more in the direct water flow, rather than using a fitting and adding CO2 right at the side of the reactor where water flow may be less than in the center of the stream. Have you noticed how creeks and rivers have faster current in the center with slower near the edges? I think that applies to reactors as well, so I do go for the somewhat harder job of drilling a really tight hole and using the trick of a really sharply tapered tube and pulling it hard enough to stretch to make it fit really tight and then when I release the pulling, the tube opens and really does a good job of sealing that doesn't need silicone, etc.
I can't say much about the flow but it would seem like a good bet to try at that price and ease of doing the addition. I like to check several sites before jumping and it takes the combo of shipping and price but that seems like a decent value, to me.
I use several Sunsun and they do have thinner plastic but the cost of repair parts is so much lower that I feel I can replace something if/when I do break it. So far, so good.