My answer to this question, having been a victim of this economic crash, is bug bounty programs. Chaos is a ladder. All this outsourcing, layoffs, and AI slop is an opportunity. That Apple AirPlay wormable RCE CVE is an indicator of how bad things have already gotten. It's pathetic how far even Apple has fallen in this race to the bottom.
These companies are running on fumes. They cut to the bone, through the bone, and everything is being held together by a thread.
But security research is really far removed from the skillset of a startup app developer. Realistically, even if you were capable of learning, which most aren't, it'd take longer for you to get up to speed than it would take for the market to improve.
The more relevant answer would be to bootstrap an MVP and pitch it to investors to get funding to scale. There's no piecework model for consumers like "install can lights" or "build a she-shed."