Edit: for the average american footprint, you can easily find the stat that the US emitted 5.268 GtCO2 in 2018. There are 327.16 million people in the US. From that I get more like 16 tons/year per person, so 20 is out of date. Of course, we have to get to zero with sequestration on top of that.
Cheaper than the Iraq war....
Mass production is a thing that brings costs down, so some of the carbon offset programs could take advantage of similar effects.
You're definitely right that some of these projects aren't infinitely scalable though. There are only so many gas stoves used in northern Uganda to be replaced..
For example, you could "offset" the effect of buying a daily latte on your household budget by just continuing to buy them while your partner promises to skip their own daily latte. Despite the offset, your bank balance would be lower than if you had just stopped buying them.
There is no known way to remove carbon at a scale that would make a difference and a cost people would accept. As almost all carbon from extracted fossil fuels is now in the atmosphere and ocean, it would amount to running our fossil fuel extraction in reverse.