Now iOS 0-day is worth up to $2,000,000 on gray market so Apple kind a take it seriously.
Unlike Apple or Microsoft buying and selling exploits is their only source of income so they have no motivation not to pay. Reputation is much more important. Also legal system does work in Israel.
You can even reach them via Linkedin and even demonstrate and sell in person with all paperwork. No risk here because they will re-sell them for much more.
Having it both fully anonymous, safe and in crypto will be harder. You need to have a trusted friend with right connections in industry not to get scammed.
Naturally there are other kinds of bugs as well.
However reducing 70% of root causes, saves a bunch of money already.