I wonder if this is technically possible? Make a coin with one billion APR staking returns.
Possible but it will turn out into a scam.
I'm thinking of a Peercoin fork for example where the staking returns were just set to an absurdly high level. I understand that something would have to be done to not hit integer limits, maybe there could be multiple tokens internally where each level of tokens is one billion times the value of the previous level.
Everyone has an idea until they apply it to their projects and see the actual result of it. Most of the high APR projects will decrease when people patronize and actually stake on it. But with such high APRs, it's unreal.
In a country where staking income is taxed as capital gains before even selling, this would be instant financial suicide probably, if it held any value? Of course it would be problematic for exchanges as there can be only so many zeroes in their prices.
I guess that there won't be any demand with that because people nowadays are going to be aware of what are the high APR does.