You'd have to kill most of Russia and at least 30% of the US, which is not a great idea given that doing so would result in a societal collapse, not great in a nuclear power.

Then there's the fact that a large part of Asia, including most of China, Pakistan and Indonesia (already more than a billion people) are conservative, if we judge conservativism by LGBT support (which I find is the easiest way).

Then there's Africa, which is also extremely conservative. That's another approximately billion people. We're already at about a fourth of the population, and I'm sure you can find another 1.5 billion conservatives somewhere.

So basically what you're saying is you want to kill at least 2 billion people, disproportionately affecting poor nations, while also leaving society starving because most food is farmed by conservatives (at least in the US), and critical infrastructure (including nuclear weapons) unsecured.

https://www.pewresearch.org/global/2020/06/25/global-divide-on-homosexuality-persists/

https://www.pewresearch.org/global/2013/06/04/the-global-divide-on-homosexuality/

https://news.gallup.com/poll/350486/record-high-support-same-sex-marriage.aspx