But I wonder can you contribute to a country’s society without living there yet?

Yes you can. There are ways to do so.

The only thing I know how foreigner can contribute to a country is by paying taxes but that is impossible if you are not working there so are there other ways?

Paying taxes is an obligation, not a contribution

So, I’m considering going back. I have applied for several jobs in the US, including at the company I last worked for. But I don’t have anywhere to stay or any funds. My friends are all going through their own hardships and can’t take me in. I don’t have any family I can stay with either. Does anyone have any experience in this sort of thing? For reference, I would likely be moving back to the Seattle area.

You mean like better financial planning and making sound decisions, having financial security before moving to another country? Try r/personalfinance