How to find startups and get noticed by hiring managers or founders easily

I have applied for more than 300 jobs. And didn't get back any response. These are the jobs which I found on linkedin in which most of them have more than 200 applicants.

For context I'm a full stack developer with 2 years of experience currently working in a startup with a CTC of 7 LPA.

I tried cold emailing and messaging in linkedin.

I got two interviews after messaging directly to HR via LinkedIn.

And I'm targeting less popular startups with less competition.

Now my question is where can I find those companies And what's the best way to reach out.

Also one final question, I'm a single developer in my company and I'm handling the tech alone make technical disitions, design databases, architect projects, and manage deployments. Can I point out this as a good thing? Will companies get impressed by this?

And how much salary can I expect?